interfacing with the windows api

[lee]

I'm trying to write a short windows application, and I need to define a windows
class object. In C this is simple since the class is defined in the windows
header file. Unfortunately, I can't create a wc object in my D program. I tried
importing the header file, but the class definition doesn't carry over into the
program's namespace. Moreover, this is just part of a larger problem. I have
been experiencing problems importing user defined data types from C header files
in general. If someone could explain how D interfaces with C code, I would
really appreciate it. 
Thanks
Lee