Ok. If you took out your videocard, I gurantee you would see the same thing as the picture of the card I posted earlier on newegg, since you have a 8400.
you will see a place with like 6 pins on the actual card, this is where you would plug the VGA port into, you would unscrew the backplate, take it off, plug the VGA port in on the card, replace the backplate with the backplate with both the VGA and DVI port openings on it, screw that in, put the card in, and you're good to go.
This is all assuming that you have the parts that came with your videocard. If you don't have this, then there really is nothing you can do short of ordering a new video card. For $30, it's not terribly expensive though.