well basically it's an animated gif ... not 2 hard if u have the patience to do it. I personally like to use unFreeze as my animator.
from scratch to make a simple blinking avatar u.....:
1. pic the pictures you want to use....crop and edit so they're all the same size and shape
2. decide what order they're going in...( I like to put them in a seperate folder in my comp)
3. make sure all the images are gifs
4. use unFreeze (or other animating program) to animate, [you can decide the rate each image stays on for, and if u want it 2 infinate loop]
there are of course other, easier programs 2 do stuff like this, but I like this one personally ..... pm me if u totally didn't understand ma lil blub here ^