i ditched the photobucket mobile app because it was chewing data.
you do it the same as normal, copy the image tag + url to the forum. i've ususally had to view the full site to access that link (or "share" the photo in an email and snag the link that way, then manually type the img tags).
Click on the image whn it comes up press the menu button on the phone the one that looks like a garage door lower left then hit view links then just touch the link u want it will automatically copy it then come here and paste it.
i always just create new albums name it, go to the library, pick album i want to share and on the right hand side it will have 3 links, top one pm/im link click on it, it will say copied and come back and post it!!!