acquia slate theme css modify fluid

Hello i would like to change the Color / background on the Theme...

I found out that i can use the local.css for all my wishes.... but how can i change colors and how can i use an background image instead of only one color background???
Can someone show me some examples???

Kind Regards, OrinocoDelta

In http://drupal.org/node/397242 @bigmac83 provided some great code to change the column widths of the acquia slate theme. These were done for a 1440 x 900 screen resolution.

B4 I try to do anything, i wondered if anyone had any idea on how this would work and render for lower screen resolutions? Thanks in advance.

Please please please! I have zero training in css and have learned the hard way (many hours trying to modify .css file) that makiing this theme even a little bit fluid is problematic. My site really needs this functionality. I know that when using 1, 2, or 3, columns things have to match the header content wrap width in order for things to line up, but how would one break that? Say, I don't care if the sidebar left and right don't match the white header.jpg but I want the sidebars fixed and the middle content fluid to the screen.