Koronis Phlox

Hi, I'm also new to Blender, it's my first 40h week Well, since i've uploaded my first Mesh, I'm searching for an answer how to apply a shadow under it. I've uploaded my fifth Mesh (and a lot of Test-Cubes) and didn't find any solution. So, is anywhere a tutorial how to, or do i have to add a transparent texture with shadow inworld at the plane at the bottom? In Blender everything looks nice and smooth, in SL my plane is black or white (depends what kind of color ive choose for the new image at uv unwrapping), with baked shadows at it. Thats not what I want I havent tried it in cycles render or with nodes. Im a Noob! Sorry for any made mistakes in this post, english is not my first language. And thanks for help in advance. Koronis