I think winbase.h defines these functions.
I've only used them in MFC, so the framework may have automatically imported other necessary libraries, etc. Either way, if you look the MSDN with the above functions, I'm sure you'll figure it out. If you need to enumerate through sub-directories too, check the SetCurrentDirectory() function too.
HANDLE hFind = ::FindFirstFile("c:\mydir\*.*", &fd);
if (hFind != INVALID_HANDLE_VALUE) // make sure valid
if (!(fd.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY)) // don't care about directories
} while (::FindNextFile(hFind, &fd)); // enumerates contents