I have a WD my passport and when i plug it to my pc, the light turns on. Eventually, i doesnt appear on my pc.
I assume you are not using an external power supply, but are depending upon the USB port to provide adequate power for the device? If so, that is not a good idea. On most computers only 1 or 2 ports have enough power for a hard drive. Try it with the external power supply.
I have used a passport, and it required additional software. Not sure if that's still the case. Did you install anything?