Change background color.

Hi, I was wondering if you could tell me how to change the background color of the area where the logo could be placed i.e. only this area and not below the menues. For instance in this case the logo background is black and I would like to make the whole area black so I dont have an frame from the background. Secondly, do you have any image/link where the definitions/names of the different areas of the webpages is called so it could be easier to located the specifik variable in the CSS template. thanks!