How to change color of the Nav bar ?

[davidf]

I think this is the nav bar? But not sure, I have tried to change the color with the css style and only changed half of the bar. I would like to change the box to the left as well.

I know the 1st alt will do it but it changes the page.

I post two pics to better explain, the first show what I want to change and the second the half change.

Thanks,
David