I want to do this.Two drop-down lists

First contains hard-disk drives on my computer

And the second drop-down i want to contains files in the drive that i choose in the first drop-down

Here are the files

I am using Visual Studio C++ 6.
Can you tell me or give me links how to scan hard disks on my computer and add them to the first drop-down then to see the files in this drive in the second drop-down