How to change background and broder in vBulletin

[HostGi.com]

I need to know how to i change the background
colour for vbulletin because at the moment its a dark grey
on either side of the content and i want to change that to white
and i need to to know how to change the outer border colour next
to the background colour i need to change both of these
could you tell me which .css file i need to edit and where it
is located or in which template i must make the edit.

Image of how it looks now:
http://img814.imageshack.us/img814/221/76940572.png

Image of how i want it to look:
http://img842.imageshack.us/img842/986/30192529.png

URL of site:
http://webgamecreator.com/

please tell me what i must change.

--------------- Added [DATE]1284429637[/DATE] at [TIME]1284429637[/TIME] ---------------

If anyone else wants to change this goto:
Style Manager > [Style Name] -> Edit Templates --> CSS Templates ---> vbulletin.css

you can edit the main background things and borders