What template/style do I edit to do this?

[ChevyGrant]

Hi,

I have been trying to figure out what I should edit to change the color of the following thing:

http://www.biteboom.com/files/2537_z3xlq/fsa.png

It's the bit that's white, and I also want to know what to edit for the post background - for example when people post, it's currently white, but I want to know how to edit that color for the posting and on the main index too.

So basically this background color too for the posts:
http://www.biteboom.com/files/2538_m5txf/asfa.png

Thanks in advance.