Im trying to make a mp3.com type theme but have trouble with menu

http://img291.imageshack.us/img291/5339/ssph3.gif

in the image you can see the top menu (home - genres - mp3 players - etc...)

and there is a submenu, if home is slected then the submenu shows (rock & pop | hip-hop | alternative | etc...)

I want to make similar, depeding on category or section of site user is in.

How can I make menus like that for my theme?

any code or theme like this already?

thanks!