How do I make alpha-masked materials in 3dsmax?

I am trying to make some high-res renders of trees. When I set the transparency to the texture alpha, the texture is masked, but the material shows up gray in the parts I want transparent. How do I make the texture alpha channel indicate where the material should be see-through?

Try looking in the user ref guide under "Material Editor, bitmap", it will explain how to it all works.

Oh I see, thanks.