Insert Post Body Colour

Hello community,

I have the following problem:

I the theme "Games" I would like to change the background color of the Posts "post body" so that settles out from the background.

What areas I mean, I know exactly framed into white here: http://www.xup.in/dl,15312292/Games-Theme_BodyColour.png/

At what points I need to adapt the code in this theme? I've tried different things, but not get the desired result.

Many thanks and regards,

Jai