Somebody know how to change background size and color of navigation panel where are [home][join][members][forum][photos][something else]?

If you see mine http://socialme.yupiway.com it is shorter than main panel (I will need change width size and height by the way, it is so wide for my test) and I would like to change dark gray color for brown or green.

Theme is Showcase.

Thank you guys you are awesome.