I think he means the avatar. To get an avatar you go into your control pannel (there should be a link at the top of the page) and just look through everything in there. Somewhere is the option of picking an avatar. As for a signature, I think you just put some HTML code in the 'signature' box or something. I'm not sure, I got fed up with by banner so I just forgot about it.
EDIT: Oh, and you can click the edit button to write additional stuff to your previous post instead of double posting, too.
![Winking Fuzzle](images/smilies/fuzzlewink.gif)