Open system CPU box. You may have to figure out how to do that. Check the website for your computer if it is not obvious. Sometimes there are screws in the back and sometimes there is a latch that allows one side to open. You can leave the system plugged in to enable a good ground. This is helpful in discharging any static electricity you have. To do this, touch the frame or the power supply.
Locate existing hard drive. See pictures below.
Carefully unplug ribbon cable from back of drive – note the cable’s orientation – pin one is red
Unplug power connection (white Molex connecter)
Hard drives usually use what is called an IDE interface. IDE stands for Integrated Drive Electronics. Modern systems have two IDE ports on the motherboard. Each port can have 2 IDE devices. Older systems used a master/slave designation but the Cable Select (CS) setting is probably easier.
This is the only tricky part of the installation. Both drives need to be set with small jumpers located on the end of the drive that the cable plugs into. The jumper block is next to the cable connection (circled in red). Most systems have a CD drive, which could be set as either the slave of IDE port 1, or the master of IDE port 2. Most (but not all) ribbon cables have two connecters for devices and one connecter for the port on the motherboard. Again, setting all the drives to the CS setting is probably the easiest. That way the hardware figures it all out. If you want to use the master/slave setting make sure your main hard drive is the master and the second drive s the slave. Then you could use the other (second) IDE port on the motherboard for the CD drive set as master (or single drive) by itself.
On the back of the hard drive is a jumper block with (usually) 3 different positions. Settings will be printed on the top of the drive (circled in red). Again, setting all the drives to CS is easiest. It may be helpful to refrain from mounting the new drive until you make sure the jumper settings are correct.
Mount both drives in the chassis close to each other. Use IDE port 1 and a double-ended connecter to connect both drives to the port on the motherboard. The cable should still be connected to the motherboard. The red stripe goes next to the power connecter. (Pin 1 is on the side of the connecter that the power connection is on.) Also the connector is usually keyed with a raised part in the middle that fits into a corresponding slot at the top of the jack on the drive. This will make it impossible to plug it in backwards. However, make sure not to use too much force on any of the connections.
Make sure CD cables and all hard drive cables are connected – including Molex power connecters. Make sure you have set the jumpers. When you power up the system, it should recognize all the drives. When the system boots up, it may ask you to format the new drive by clicking OK at the prompt.
The system should recognize all IDE devices and list them at boot up. If not, your jumper settings are most likely the problem. Once all is well, button it all back up and you are done. The second drive is great for additional storage and backups.