If you never had a discrete card installed before...
Put the card in the PCIe x16 slot.
Move the monitor cable from the integrated video port to the card's video port.
Boot to Win and run the driver installation program from either the DVD or a download from
http://support.amd.com/en-us/download
The download will be the latest driver. The one on the DVD will be an older driver. Either will work, but the later one may have bug fixes and updates for newer games.