Background / white space, menu width, menu font

Hello.

I have a few questions below:

1) Background color: I'd like to change the yellow background to other color. I noted that you have five styles to choose from BUT I'd like to customize my template. Where do I change these values? I couldn't find those values in template_css.css.

2) How do I reduce the white space between the yellow background and the picture?

3) How do I reduce the width of the menu?

4) How do I change the font?

See attached picture.

Thanks.