Flash 8
Basically you need to buy it, I think I should recommend you not to use this program if you're really new to animation, I prefer you use
PIVOT first before stepping to another animation software. I started animating with Pivot then moved on to Flash 8 so I can be an animator just like Hyun or Terkoiz (but that would never happen to me lol). You can use this program even though you didn't used Pivot or Easytoon before, but it would be harder for you (I think lol). Most people here in SP uses Flash 8 so yeah c:
Pivot
FREE program, created by Peter Bone (correct me if I'm wrong, I barely (or rarely? I'm bad at English) uses Pivot anymore :c) Use this if you're new to animating stuffs, simple animation software because it's not that really hard, you're just going to adjust the pose of your stick man frame by frame unlike Flash 8 where you need to redraw them frame by frame. It's also hard when doing an effect on your Pivot animation, but there's some site where you can download awesome effects that you can use if you're lazy enough to make one.
DROIDZ is the best site where you can download stuffs for your Pivot animation.
Easytoon
Actually, I only used this program for like 2 times, can't really explain it but it looks Flash 8 where you had to redraw the guys frame by frame, although I think it's easier than Flash 8 but harder than Pivot (lol xD). Well I can't really explain this thing for you but try using it and see if it's easy :3
I apologize for being bad at English, I tried my best to help you C: