Making transparent textures?

Just wondering, how do make textures transparent? I’ve been trying to turn up the translucency but to no avail. Any ideas?

I created an interior to an eyeball and I created a seperate high poly exterior that is supposed to be shiny and clear to give the eyeball a wet and shiny look.

try clicking raytrans button

Nuttin. :-?

Ok, that worked fine but everything inside the mesh appears to render as black? I want a regular mesh inside a transparent/reflective mesh.

Also, why do you have to render it in order to see the transparency? In almost every other application you can see the mesh as being transparent in the 3D view as long as shaded view is on.