As has been adviced, to upgrade your video card, you also need to upgrade your power supply, as it is does not have the amps to drive any but the lowest of entrylevel graphics cards, and even that is borderline.

Any modern PSU you get that can run the card, should have two PCIe 6 (or 6+2) power plugs specificially for graphics cards.

You will want to get a decent quality one of 400W or better.