hi im some what new to unity and i make a level in google sketch up 8 and when i inportat in to unity as a FBX it goes in and it looks fine but when i put my player on the ground he falls through it as if it was not solid what do i have to do to make it solid
The answer to your question is quite simple.
With the model you want to enable collisions on selected, simply click on Components → Physics in the editor and select the collider type that best suits your model.
That should stop your player from falling through the ground.
thanks that did help just one thing and im sorry to bother you but my thing is so different i had to make my own mesh but i dont know how to make it in to a mesh
As LineBreaker said, add a Collider by going into Component, Physics, and then selecting the collider you want. For your case, I think that what you need is a mesh collider.