I know I sound silly asking, but I really don't know. The pictures that are next to people's screen names..how do I make one for myself? Any help would be greatly appreciated.

Windows Paint, Adobe Photoshop, Jasc Paint Shop Pro

Just use picture editing software.

Yep, edit any image down to like 80x80 or 100x100. Some images reduce better than others. There's also a limit on how many KB the data of the image can be, so you may have to skip most animated images, and you'll almost certainly have to use a function on those graphics programs called "optimize", which shrinks the data size for quick loading on the web.