This is where things get tricky, because to understand where you're placing you're stats will require a basic understanding of the pathfinder system or a firm grasp on your character concept. I recommend taking some time looking over the basic rules of the game and learning a bit about the system on your own.
The numbers don't make the character, you make the character. But the numbers do serve to project your character idea into a world. Remember, especially when starting at level one, that this is about developing a character. You shouldn't be near your characters maximum potential at the beginning and if the dungeon masters perimeters aren't high enough for your character to exist the way you imagined, consult the dungeon master as you're character idea may be too strong for their world.
It may be hard to decide what stats you want to be your high numbers. Luckily for you, if you're reading this tutorial you must have access to the internet. Feel free to look up guides on the classes you want to play if you need help figuring out which stats are important for the character you want to play. But remember, they're just guides. If you want to play an intelligent warrior, you can.

Most dungeon masters use the point buy system these days, as it's the fairest and easiest way to ensure people are being honest about their stats.
Here's a point buy calculator.

Ability scores explained: Generally your six abilities are split into two categories, Physical and Mental.
Physical abilities:
Strength: Governs few skills, but establishes how accurate and damaging your character is with most melee weapons. It also determines how much weight your character can carry.

Dexterity: Governs many important skills for stealth, also contributes to your armor class with dodge bonus. Establishes how agile your character is and how accurate your character is with most ranged weapons. And also modifies your reflex save.

Constitution: Governs no skills normally, but establishes your characters bonus hit points each level based on its modifier. It also modifies your fortitude save, which is a very important save to succeed. Represents how sturdy your character is.

Mental abilities:
Wisdom: Governs several skills, establishes how perceptive your character is and modifies your will save. Also an important stat for many class features. It's hard to describe exactly how important this stat can be.

Intelligence: Governs many skills, establishes your bonus skill points and many class features. Represents how intelligent your character is.

Charisma: Governs several skills, establishes how sociable your character is and how good at performing they are. It is crucial that at least one party member be competent in this stat.

MODIFIERS, WHAT ARE THEY AND HOW DO THEY WORK?
The base human average for an ability score is 10-11, or in other words no bonus, no negative. For every two points past ten your modifier becomes plus one.
Example: 12=+1, 14=+2, 16=+3, etc.
These modifiers are then applied to the skills and other character statistics, instead of the actual ability score. Generally the ability scores only exist to create the modifiers.

Race: Checklist
1: Find the race list on the SRD and find races that interest you.
2: Read about the races culture, behavior and abilities.
3: Comprehend the race and make sure it meshes with your character idea.
4: If your race isn't from the core books, make sure your Dungeon Master approves.
5: Observe how the race changes your ability scores and apply those changes to your character sheet.
6: Apply your racial traits to your character sheet.
7: Apply your races default languages and bonus languages of your choice to your character sheet.

Class: Checklist
1: Find the list of classes on the SRD and find a class that interests you.
2: Read about the class and it's alignment and make sure it meshes with your character idea.
3: Comprehend the class and it's role in the party.
4: If your class isn't from the core books, make sure your Dungeon Master approves.

Hit die:
This determines how many hit points the class has. Basically whenever you level up you roll your classes hit die and add your constitution modifier to the result to determine the hit points you gain each level.
Important: At level one you always get the maximum of your hit die and add your constitution modifier to establish your starting hit points.

Starting wealth:
Just beneath hit die, you should see starting wealth which tells you what you need to roll to determine your characters starting gold which is used to purchase gear that your character will start the game with. It depends on your class how much starting gold you get. Otherwise it's pretty self explanatory.

Class skills: Checklist Your skills are determined by your class.
1: Find your classes skill list.
2: On your character sheet check all the boxes of skills your character now has because of your class.

Skill ranks per level: Explanation
On each skill in your skill list on your character sheet, you should see a spot that says ranks. You may only have as many ranks in a class skill as you have levels in classes that have that skill.
So at level one your maximum ranks is one, HOWEVER. The first rank in a skill given to you by your class grants you an additional plus 3 to that skills total score. A Myth Weavers character sheet will automatically calculate this for you.
Each class gets a certain amount of skill ranks per level plus their intelligence modifier. You may spend these ranks for a rank in a class skill at a one for one basis. If you wish to increase a none class skill, it cost two points for one rank and also doesn't give you the bonus 3 points to the score that you get from class skills. You may spend these ranks for ranks in skills until you run out, then you will have to wait to level up.

Base attack bonus: Checklist
1: Locate your classes base attack bonus, appropriate to the levels you have in that class.
2: Apply this base attack bonus to your character sheet where it says "base attack bonus".
3: If the base attack bonus is 0 then apply nothing.

Base attack bonus: Explained
As the name suggests, it's the classes base bonus to attacks. Some classes start with a bonus, some don't. Depends on your class.

Saving throws: Checklist
1: Locate your classes saves, appropriate to the levels you have in that class.
2: Locate your saving throws on your character sheet.
3: Apply your classes saves to the base on your character sheet.
4: If you're using a Myth Weavers character sheet it should already be calculating your saves totals.

Weapon and armor proficiency: Explained
Basically all classes have a list of armor and weapons they may or may not be proficient with. Some classes have a very limited list, some have a huge list. They usually categorize it in terms of "simple" "martial" and "exotic" weapons and "light" "medium" "heavy" and "shields" for armor. Your character can only effectively use weapons and armor that they're proficient with. You may spend your starting gold on weapons and armor, make sure your dungeon master approves of your gear.
But you will want to wait until near the end of character creation to worry about purchasing armor and weapons.

Class features: Explained
These are the goodies, the little extra that makes your class what it is. Barbarians can rage, witches get familiars. Each class has something special waiting for you.

Class features: Check list
1: Locate all the class features, appropriate to the levels you have in that class.
2: Read about the features and comprehend what they do and how they function.
3: Apply the class features you have at your level to your character sheet, so you don't forget.
4: Make sure to use your class features.

now you get to spend your precious starting gold, on items to begin the game with. At level one it's unlikely that you'll be able to afford anything too awesome, but if you play your cards right you can start with some good gear and that's actually a big deal when it comes to level one survivability.
If you're unsure about what items to get, use the internet to look up information on good starting gear for characters of your class.

Spending gold: explained
This part is all about information, so I'll try my best to provide lists that show gear and pricing in an official way. What you want to purchase depends almost entirely on the character. You may be interested in nice armor, or potions, this part is totally up to you.

Spending gold: Checklist
1: If your character uses weapons and armor, look here for a comprehensive list of weapons and armor pricing.
2: Pick out weapons and armor you like and that your character can use.
3: Look here for adventuring gear.
4: If your character cannot see in the dark, purchase something that can light the way.
5: Purchase some food and water.
6: Probably want to purchase a back pack and bedroll.
7: Probably want some rope too.
8: Finish up purchasing your fucking nick-nacks
9: Calculate the weight of the items your character has and determine how heavy of a load they are carrying.
10: Make sure your character isn't too weighed down.

Traits: Explained
By default, each character starts the game with only two traits and can gain an additional one if they wish to also take a drawback. These traits can slightly tweak your character, but also add flavor to your character.

Traits: Checklist
1: Locate the traits and drawbacks lists on the SRD.
2: Find traits that interest you or sound like something your character would have.
3: Read about these traits and comprehend them
4: Apply desired traits to character sheet and don't forget about them.

Calculate armor class:
Make sure that your armor class is properly calculated after applying the modifiers from your armor. Remember many armors have a maximum dexterity bonus that restricts the amount of your dexterity modifier that you can apply to your armor class.

Calculate weapons attack and damage:
Pretty self explanatory, but this is based on your knowledge. Two handed melee weapons, one handed melee weapons and ranged weapons all calculate differently. Look up the ruling if you get confused, if this is a problem I can make an explanation for this part.

Make sure your dungeon master is okay with your character by showing them your character sheet. If they don't like it ask them why, then make changes accordingly and try again.