I’ll give it a shot.
I guess it depends which section you want to change. I made a portion an obnoxious pink, for example. http://i51.tinypic.com/xnzrib.png In your style.css file you can go to your Header section and add the following bolded line, replacing the hex code with a color you want.
#header {
background-color:#EED2EE;
border-top:2px solid #F4F3F1;
height:133px;
}
The white behind it, however, seems to be dictated by a repeating white background image that you can change as well.
#wrapper {
background:url(“images/wrapper-bg.png”) repeat-x scroll left top transparent;
}
