How to write an interface for video player?

For my school project, I have to write an interface for an MPEG player.
I want to use other people's codec to do this e.g. Xing MPEG's player.
I have the following problems:
How to use the functions in a compiled .dll file?
How to write the interface for displaying video in Visual C++?

Thank you.
Louis

Mate I reckon you should drop that subject....
(If its an HCI subject for first year or something like that, they probably just want to see how you'd design the interface, so mock it up in VB or sommit)

Mate I think you should not assume anything. This is not an HCI project.