A #0 Cross head screwdriver
Unscrew all 4 screws
Pull out the end where the USB port is located
Pull out the board and harddisk
Put the harddisk and board on the work table
Pull out the harddisk by pull the pins out of the connector on the board
Put in your hard disk by pushing in the pins at the end of your hard disk into the board.
Reverse the steps of taking out the hard disk.
Congratulations, you have successfully put a hard disk into a portable drive