After installing a hard drive, you will want to install any ROM or floppy drives you may want in your computer.
Go ahead and remove the drive from the packaging. Your drive should be an IDE drive. All that is needed now is to slide the drive into the case from the front. Make sure that the holes on the drive match up with the holes provided on your case. Next, fasten the screws and make sure the drive is secured in place.
Finally you will want to attach the drive to your motherboard and power source. Use the provided IDE cable and attach to both the back of your drive and corresponding slot on your motherboard. Next, find a free 4 Pin Molex cable on your PSU and attach that to the back of your drive.
The last step of assembly is installation of a Video Card and Sound Card, if you choose to do so.