Connect the diskette drive ribbon cable first. As shown below, there is a tab on one side of the connector.
diskette drive connector
diskette drive socket
Align the connector with the socket so that the tab on the connector lines up with the notch in the socket. Make sure the holes in the connector fit over all the pins in the socket and then push in the connector.
Caution
If you do not correctly align the holes with the pins, you could severely damage your computer when you push in the connector.