Thread:KillFeedz OG/@comment-1142365-20120314211028

It's done with CSS. You can find it on here. The code is:

body.mediawiki { background:#262626 url(IMAGEURLHERE) fixed center top no-repeat !important; }

You'd need to add it to MediaWiki:Wikia.css and put an image URL in where it says IMAGEURLHERE. 