@Everyone: I suppose this goes for everyone here then. If you don't know how to change your profile picture, then here's how.
First things first, you will need to be using the default forum skin for this to work, not the mobile one. Not many people use the mobile skin anyway but just keep that in mind. So, with that out of the way, go to the top right of the page and press the "Settings" option. This is right next to "My Profile" and is above the search bar. Then find the "Edit Profile Picture" button on the left hand side under "My Profile" and find a photo within the size limit and either copy and paste the link or download it to your computer and select it. If you are looking for the place to put the photo that will appear on every post, then that's your "Avatar" and it's underneath the "Edit Profile Picture" option and stuff.
Also, for profile pictures, they can be either still images or gifs, and the dimension limits are 100 x 100, and the file has to be 64.0 kilobytes or less.
For your avatar, you can have either a still photo or a gif too, but the size has to be 185 x 185 or less.
Hope this helps! And to those who are new and didn't know, welcome to the forums!