Your video card is what produces the image on your screen.
If it's a laptop it's built into the motherboard and on some budget desktops. Other have a separate card that slots into you motherboard.
Direct X is a Microsoft product to help your PC create better graphics etc.
Depending upon the age and type of you video card it will only support older versions of Direct X, Windows 7 now supports Direct X 11
Find out your make / type of video card in 'Devise Manager' and check on the manufactures web site for it's specification.
If your card will support Direct X 9 or higher download it from click here and run. If you are not 100% positive your card will support Direct X 9 do NOT install it.
You may need a new video card to run this software !