ground plane + AE beta ?

HI all .... i'm pretty adept at AE overall ... less so in the 3D space .. 

I'm on the Beta version ..... and have been working with the Draft button .... i'm wondering if anyone has seen any good tutorials (videos or otherwise) on the ground plane  ? I'm trying to natively build a 3D room in AE 3d space, place 3d objects, cast lights and shadows on the walls etc. 

It seems (?) you should be able to pin a shape onto the ground plane and make a floor out of it ? 

any advice or guidance would be appreciated .. .sjk