changing the area of navPanel

Hi friends:

Customers want to change the look of portal desktop to be a fresh new one, just to be like their own news website,

I can change masterhead to look like their website's header, but I don't know hot change the look of the area of navPanel

Container ( I am not sure if it is ok to say so, maybe detailed navigation) to make look to be the same as their navigation

panel, just find that http://www.yahoo.com/ also have left navigation panel, on top of which there is "MY FAVORITES

Add Favorites ", I just want a frame of navigation area look like this one, the size , the color, and effect , don't need to add icon

to every tree node. what is your way to change it ?

hope you can understand me. could you please kindly discribe it in detail ?

thank you very much