[SIZE=7pt]Well, there are different ways to make avatars.[/SIZE]
If you just want something simple you can just take a picture and crop or resize it to 100x100.
Or, if you want one of those fancy icons/avatars like the ones pros make at Livejournal, you have to use a program.
You can use gradients and textures to change the look of it and add decorations when you're done.
I've found many avatar/icon tutorials on Livejournal, but I'd rather not post them on here ^^
If you would like some links or more information just pm me.
(If you're thinking of using a program I'd recommend any version of Paint Shop Pro.)