Hi Sara,
Click on your member control panel at the top left of the page. Go to Edit Profile. In your signature box tap in (IMG)(/IMG). Both of these should be enclosed in square brackets rather than round brackets that I've used here, but for some reason I'm getting a red cross of death when i try to post this. In the space between the two sets of square brackets copy and paste the url of your chosen picture. That should work, although you won't see your sig until you post a new message. Your chosen image will need to be on the internet, so if it's a picture on your own computer you may need to use a photo sharing site like Photobucket. If you notice a link on the left of your signature box to ''BB codes'' it explains how to add various other things. Hope that helps.
Edited by seventhsojourn - December 02 2010 at 18:01