when you post, there is a set of smiley faces and then a set of icons above that. hit the one that looks like a beach with trees on it. that will bring up something that looks like [img][\img]. put the url (web address) of the picture in photobucket in between the two middle brackets, so it would look something like this: [img]http://www.photobucket.com/rodrunnerspicture[\img]
you get the url of the pic at photobucket underneath the image where it says "direct link"