You go to the User CP link at the top, and then in the options on the lefthand side, click "Edit Signature". Then just insert the link to the image with
IMG yoursite.com/picture.jpg /IMG
but remember to put [ and ] around the IMG and /IMG
or if you want to use you own picture, make a account on www.photobucket.com and upload it the copy the link with yourpicture.com and past it into your signiture
Comments
IMG yoursite.com/picture.jpg /IMG
but remember to put [ and ] around the IMG and /IMG