Having a bit of trouble, I don't seem to see the Signature option *Even though I believe I've nailed the requirement* The other is why is my avatar not 'animating'? Its a .gif, similar to Jazziette's. Any clue or have I missed looked something? (Stupid of me >_<)
You should be able to see the option if you go to your User CP (you'll see the link on the top left of every page) and picking the Edit Signature from the list on the left. I'm not sure about your avatar though.
There are several online options, upload a gif select new size and download new gif. The one I used to use doesn't seem to exist any longer, so I don't have anywhere to direct you.