that made the whole thing wider again...
Code:background-size: auto 100%;
Are you wanting to center the background horizontally and vertically?
background-position: 50% 50%;
If you are just wanting to stretch it a certain way, or enlarge the canvas to add more graphics around the original image, maybe a graphics program would be better.
the problem is however, is that his graphics program won't allow him to stretch it anymore
Well, ok. I can scale just about to any size. Of course the bigger it gets, the grainier it gets. Same as if stretching with css.
Comex, upload it to Imageshack or somewhere and post a link and tell me what size you want.