1. On the bottom of your Dell D520 laptop, find the hard drive door to access the hard drive.
2. Remove the Screws.
3. In this step, you will either need to pry out your Dell D520 hard drive caddy, or simply remove the door.
4. Once the Dell D520 hard drive is removed the laptop, you need to remove the hard drive caddy. There are usually four screws to remove from the caddy.
5. Simply Insert the new hard drive into the caddy. Place the screws back in. Install your new Dell D520 hard drive.