navigation button on top of background

[jjmaster-j]

Hello,

I am fairly new to css. But, what I want to accomplish is to have a green bar behind the vertical navigation buttons, like apothecarecolsvc.org. The reason I want the green bar behind the buttons is because I want it to dynamically follow the content on the right side. How would you have a layout on top of another? Is it what float position is for? Is there a tutorial available somewhere?

Thanks in advance
jjmaster-j