Hows this Carl?
What you need to do is copy the complete URL below (including the [img] tags)
Code:
[img]http://img4.photobucket.com/albums/0703/Thrush/Signatures%20avatars%20and%20wallpaper/cossie_carlPfBBsiggy.jpg[/img]
Then go to your Profile (top of page) scroll down to the window for your signature, and paste it in there. Make sure you get the first [img] and the last [/img]...