First of all, in general you can't just write a general program with Visual C++ that directly accesses computer hardware. That access is restricted to device drivers, which usually have to follow a certain API (like the Windows DDK or WDM) to hook into the operating system.
Most likely the PCMCIA flash card you have is already formatted with a filesystem (FAT?) by the manufacturer and should appear as a removable (secondary) storage device with its own drive letter.
If a new drive letter doesn't show up in Explorer when you plug the card in, check the Device Manager after plugging in the card to see if it has detected your card and whether it has a driver loaded for it or not.
I believe the way these PCMCIA flash cards work is they follow a form of the ATA command set used by hard drives since the early days of the PC. The flash card contains the flash storage chips plus a built-in controller that understands ATA commands. This means it should look like just another hard disk to your laptop.
