Translating step 6
Insert a machine screw through each of the four holes around the CPU heat sink, with their heads on the back side of the board.
While holding the head of the screw, place a nylon washer then a metal washer over the threads.
Using the large flathead screwdriver bit, tighten the screws into the CPU heat sink. First lightly tighten the four screws in an X-shaped pattern as seen in the second picture, then follow the same X-shaped sequence to really torque the screws down.