You'd need to use something like this method (youtube vid) to create you background (if you don't already have one) and the Do Not Scroll Background tweak from the version 7 Tweakset
Type: Posts; User: ShapeShifter; Keyword(s):
You'd need to use something like this method (youtube vid) to create you background (if you don't already have one) and the Do Not Scroll Background tweak from the version 7 Tweakset