Materials & texture

Hi all!

I know, I am totally stupid but I would like to know, how to use Blender3D. I think using materials and texture is much more interface related than modelling.
My question is: how can I apply materials on a part of an abject.
Eg: I have a cube with some subdevision:
http://str2etboy.fw.hu/cube.jpg
And I want a part of it to be eg: red and the other part blue… No textures etc… only colors:
http://str2etboy.fw.hu/cubepart.jpg
I created a vertex group for both.
How can I set the material?

Don’t doublepost - http://blenderartists.org/forum/showthread.php?t=71010