if you already have the hard drive with your operating system installed in your rig and you are adding this as a secondary storage drive then...
-make sure you have the power cable and data connector (usually sata) connected at both ends.
-you set the hard drive to "slave" in bios. if the device doesn't show up in bios try swapping to a different data port and use different data & power cables to eliminate them as possible issues. an item not appearing usually means it isn't "seeing" the device because either it isn't connected right, doesn't have any power or is fried.