You can change the side bar color in several ways. When you add color though to the side bars yo have to fiddle with the spacing so it looks centered. I think instead I'd just change the color behind the headers.
To fiddle with this in the custom.css file add these two things, then upload to your site - then you will see what I mean. I think the easiest would be to just use the second line.
/* background changed both side columns - width was 220 changed to 180 so three columns */
.custom #sidebar { background: #336699; width: 210px; padding: 0 0 0 15px; float: left; }
/* when the url background is removed the background color changes the widget headline background */
li.widget h2, li.linkcat h2 { background: #4444cc; font-weight: bold; font-size: 1.077em; text-transform: uppercase; letter-spacing: normal; margin: 0 0 0.8em 0; padding: 0.4em 2px; border-top: 3px solid #000; /*background: url('images/hr_dot_black.gif') 0 100% repeat-x;*/ }
I've been fooling around with background colors of things on a test site I set up - boy Cutland is so flexible - I really like it.
http://sdcue.org/hthitest - you can click the theme switcher option to see the three Cutlands - the changes were made in the custom file for each.
Hope this helps a little.
: )
June