For use with AMD CPUs, you need to attach the pieces shown in Figure 11 to the cooler, which is held by the motherboard frame.
For Intel CPUs, you must attach the frame shown in Figure 12 to the motherboard, as you can see in Figure 13. This frame is compatible with sockets 775, 1155/1156, and 1366.
The cooler is screwed to the frame, using two screws. You have to remove the fan in order to have access to the front screw.
Finally, attach the fan to the heatsink.