Get the IMG code, if it provides you one (photobucket does).

If it doesn't, I think you get the direct URL of the picture, while making the post you'll see an option beside the general format (opposite side of underline, bold, italicize), it will look like a small painting picture. Click that and it should ask for the direct URL of the image you want to put. Paste it in.

Im replying from a phone so I can't show you exactly where, but hopefully you'll understand.

Just make sure the option says "Insert Image", right next to "Insert Link".