Changing the colour of the theme

I am stuck at the moment, i've come to a grinding halt whilst changing a theme on my forum.

I'm wanting a dark theme, i've managed to change  a lot of the colours via the easy editor. But I'm stick, need to change the background of the actual postbit (The area where this text is).

This is probably too much to ask, but how can I change the following colours, I guess I have to manually do these via HTML/CSS options.

Anyway here is what I need to edit, the YELLOW highlights are the colours i'd like to change. 

Back in the day when I used to use vBulletin, it could edit all the HTML to get the correct colour where I wanted it, but for some reason i'm struggling with this, I think its because i've got lazy and i've not touched HTML for so long!

Thank You very much.