On the off chance this is legit (and because I have nothing better to do)...
You need to make sure your motherboard has the slot that matches your graphics card (pci-e x16 card needs a pci-e x16 slot). This information should be readily available on the box or at whatever site you're looking to get things from.
Most motherboards at this time have pci-e x16 slot(s). At this time, there is pci-e 1.0, pci-e 2.0 and pci-e 2.1. All versions of pci-e are compatible with each other. You can throw a graphics card that can use pci-e 2.1 into a pci-e 1.0 slot, and you can throw a pci-e 1.0 card into a pci-e 2.1 slot.
Other concerns you should consider are the case (do you have room to put your card in it?) and the power supply (does it give you all the power connectors you need for the graphics card? can it supply enough power for your card?). You should be able to find out how many amps your card draws, and then it should be easy to compare that to the amperage your power supply can give (you'll be looking at the rating on the +12V rail(s))