Right hellen this is what you have to do (hope I can help!lol)
If you have your image that you want in your signature....upload it to an image host. I'd recommend creating an account at [url]www.photobucket.com[/b] or any other image host that you know of.
Once it is uploaded you shoud see a tag with [img]at the start and [/img] at the end.Copy that.
Then come to TiBB and go to your control panel (theres a link in the top right of the screen) and click edit profile.
Look for the Signature box and paste the tag into the box.
It should say something like
Code:
Save the changes and it should work for you.
Hope that helps!