How to change destop picture without using any third party utilities

In the finder, click on the the Finder drop down menu (next to apple menu), then click preferences.

Hey, anybody figure out how to have different backgrounds on two monitors?
That's really pissing me off too!! I wan't a different and Randomly different picture everytime I log in on my second monitor, seems like an easy thing that apple forgot to implement...retards.

What I'd like to know is how to make a desktop picture or at least change the blue if you've disabled the desktop (never liked the "desktop" idea anyway, too messy and cluttered)