modules && type inheritance?

[MM]

I use derelics for my sdl/opengl application and I wanted to make one module to
hold all my structures. I don't know much about scope and inheritance of types
and thus don't know how to make this work :(
In my structures I use the OpenGL types (GLubyte etc.)
What do I have to do to make these types visible to other modules?
Or.. where can I read about this :)
btw. Is it really necessary to use the gl types iso d types?