Answer:
To install a hard drive, follow these steps:

Step 1: Power off the DVR and open the casing by removing the screws.
Step 2: Slide off the casing.
Step 3: Place the 3.5 inch SATA hard drive into the drive bay.

Step 1: Secure the hard drive using the screws provided.
Step 2: Connect the SATA data and power cables to the drive.
Step 3: Put back the casing and reinstall the screws.