To get an animated avatar, you can find them online by searching on google images and going to search tools, going to "type" and selecting animated. Make sure that the avatar is no larger than your maximum avatar size by either file size or dimensions.
For signatures, you can upload a sigpic. If you have an image, you can put it in your signature with the following syntax:
[sigpic*][/*sigpic]
Minus the *.
