4.Use one of your hands to hold up the subassembly or have someone do it for you. With your other hand, grasp the longer end of the hard disk drive ribbon cable that you tucked underneath the drive when you installed it. Pull the cable under the subassembly and toward the front of the computer.
5.Locate the hard disk drive socket at the front of the main system board (in front of the socket that holds the diskette drive ribbon cable). There is a notch on one side of the socket, as shown below.
notch
Pick up the hard disk drive cable and notice the connector on the end of the cable. There is a tab on one side of the connector, as shown below.
tab
Align the connector with the socket so that the side of the connector with the tab lines up with the side of the socket with the notch. Then make sure that the holes fit over all of the pins and push the connector onto the pins.