Ok, first thing we need to know is that card.
Some newer cards only support ONE VGA out and still have what looks like DVI-I, but may not carry the analog signal.
If you have 2 DVI ports, try the other one if you can.
Now once you have it all connected, you have to use your video cards software or even windows to swap screens.
Win7/8 can use START + P to switch screens.