Win32 File Switching within a directory

Hi guys,
How do you implement ACDSEE like file switching within a current directory using win32 Api. As in, in my project I am reading a "DICOM" file as input and now I want a way in which I can view the next file by just clicking on a "Button" on the Toolbar. How do I implement such kind of File Switching in the Win32 Api. Like "Previous Button" for previous file and "next button" for next file instead of clicking File->Open and all that stuff.

If I've guessed what you're asking correctly:
FAQ -> How do I -> Access a directory and all the files within it
Detailed Tutorial

gg