so, when you drag your mouse over the picture on photobucket, it will open a small box that has 4 smaller line box's in it.
Go to the IMG code and click it.
There will be a window that says "copied"
Then paste the picture here.
Any size will work with the photobucket option.
There are also some threads here if you search for them, that have detailed instructions on how to copy and past the IMG code from photobucket.
Try again, it's pretty easy.