Adding a Background Image to Posts

I have seen this on numerous forums, where a member will have put their text over top of a background different from the regular background you usually see when you post. They haven't gone in and edited the skin of the website either, nor is the post made up of an image. I've searched but cannot find the correct BBcode(s) to do this.

The posts on this thread are a good example, as I probably didn't explain it very well; http://www.platinumhearts.net/t5440-bringing-disorder-to-society

Any help is much appreciated!

You're going to want to use a table BBCode with CSS..

Code:

[table style=""][tr][td][/td][/tr][/table]

Oh, okay! Thank you so much!