You'll need a non-magnetic screwdriver to perform this operation.

1. To install a new hard drive, first remove the screw that sits in the side of the drive bay from within the computer case.

2. If you need to remove a screw from the other side and it's difficult to reach because the front panel of the case is blocking access to it, you can remove the front panel squeezing and removing the small clips at each corner of the front panel that attach the panel to the case.

Once removed, you can unscrew the other screw.

3. When the drive bay is free of obstructions, you can then slide your new hard drive into the chosen drive bay slot.

4. Line up the holes in the sides of the drive with the holes in the drive bay slot. Insert all necessary screws and secure the hard drive in place. Be sure to include every screw. If there are four holes, then attach four screws. This is important because it's vital that the hard drive is completely secure and in place. You don't want the hard drive to be able to move around as even the slightest movement can damage the needle and disk inside.

5. Once all the mounting screws are in place and secure, you'll need to connect the hard drive's power cord and the information data cable to the motherboard.