If you want a photo in your profile (an avatar - the little pic under your name on every post) then hover over the 'Profile' button (in menu bar near top of page) and select 'Forum Profile'. At the top option there is 'Personalized picture', check the middle option 'specify avatar by URL'. Copy and paste your photobucket code into that box. When you hover over a photobucket pic it gives you a list of codes - the one you want is the 'direct link' one.
If you were posting pics in your thread (hint, hint) then you select the 'IMG code' one and paste that into your post.
You can only have one pic in your avatar unless you make a flashy gif file of a compilation of pics. IF you wanted one of those I'd be happy to make you one