I strongly recommend you to read this before asking any more questions:
http://wiki.truevision3d.com/tutorialsarticlesandexamples/introduction_to_materials_in_tv3dIt is a very good explanation of the whole lighting and material thing.
I even wonder why nobody posted this before, that is what the wiki is for.
And this one by Javin really is a good starting point for newbies
