Theme's color scheme

OK, I’m trying to change the theme’s color scheme.

My question is, how do I do this? I want to change the following:
sidebar background color
post body background color
navigation menu bar background color
header space background color
above header space background color (where the logo / search bar are)

Basically, wherever there is white, I want to change it.

Here is a screenshot, where the areas I’m wishing to alter are encircled: http://i.imgur.com/r3jWy.jpg

Can you tell me, which codes in the CSS stylesheet I have to alter?

Thanks.