ComicVine's Background Pic Dilemma

I wanna put a banner on my profile page but somehow this website doesn't allow us to fill the screen, tile it, align middle or perfect fit. The profile page can only put the image on tile and never aligned properly. Is there a way to fit the image properly or can anyone tell me the exact measurement of the background (In pixels) so I can put an image that has the right size to fit the frame?

Methos wrote a very good guide on how to edit your profile.  It might be able to answer your question.