how do i change the background. i started with a page of code and am using the visual editor to edit it. and i aslo would like to ad just a simple colored rectangle. as you can guess i am ver new to this. thanks.

The background can be changed easily under Settings >Standard Settings for New Pages.

A rectangle can be added by using the Shape Tool. Click on the tool then select the shape you want. Then drag the shape out to the size you want on the page using the mouse.