okay first thing first.
get an account at
photobucket. photobucket is a service that allows you to load pictures from your computer and give them a distinct URL... so that you can load them through html and bbcode onto other sites.
load your picture that you want as your signature (onto your photobucket account), and keep the photobucket window open in the background.
then you come back to the forum... go to your profile, then go to the tab on the right hand corner that says signature.
paste the "img code" from the picture in your photobucket account (its the third down of the three urls there) into your signature box text thing.
now go back to the preferences section in the "profile" area (not the signature section) and check yes where it asks if you always want signatures to appear.
and thats about it... hopefully thats a bit more helpful.
ALSO: MAKE SURE YOU ARE DOING THESE STEPS AS YOU ARE READING... don't read this ahead of time and expect to remember, its too confusing. so keep this window open in a browser while your doing everything else and you should be good.