3 Way Gradient

Question

Hi

I'm struggling with my Gradient in silverlight. In the link below is what I'm trying to do. It's the Menu block (Top Block).
http://www.internationaltrucks.com/Trucks/

I know how to get normal Gradient, but I have no idea how to get the result that's in the link. I'm still pretty new to Silverlight and I'm not really finding anything what I need with Google.

Any help would be appreciated.
Thanks