Rusticspec, many thanks for your post

you don't need anything special to do this, all you have to do is to go to admincp>>vBulletin Options>>Styles & Language settings and in the "Use Legacy (Vertical) Postbit Template" just chose yes and that's it.
Hemanth, thanks for your post
All you have to do is to go to admincp>>Styles & Templates>>Style Manager>>Cairo Style>>Main CSS
Then in the "Page Background " panel and in the "Background" box, remove the whole line and replace it with the color code you want.