on photobucket,
:hover over the pic you want and it shows a drop down "menu",
:at the bottom of it has IMG code, click on the code,
:then on here right click where you type your reply to a thread,
:in that menu click "paste"
:you should then get an image code, something like http://i478.photobucket.com/xxxxxxxxxxxxxxxxxxx[/IMG ] will appear
:then click "post quick reply" and it should show up