Mei Tien,
You are correct. The easiest way to control the player, add sound, etc. is to
control the MCI driver. This is fairly easy to do. Download MCIAAP.ZIP, there
is a file which lists all the available commands.
The MCI driver does not give you the most control, however. For the most
control and flexibility, you want to make calls directly to the .DLL from your
code. You can find out how to do this by ordering the "Windows Player
developers kit for the .DLL" by calling 800-879-4233. It costs about $30 for
the documentation.
-Brian