To install the clamping plates on to the Flat-Pack Camera Arm, lay one of the plates on the camera arm so that the ring is centered on the hinge of the camera arm. Mark out the four holes on its corners, and drill them to a depth of 0.5" with the appropriate pilot drill for some small wood or drywall screws (in my case it was a 0.125" drill).
Screw the locking plate down, and repeat the process with a second locking plate on the other side of the hinge.
Once your locking plates are installed, you're ready to assemble the arm. Operating the mechanism is simple - by backing out the hand knob that keeps pressure on the plate a couple of turns, you give the teeth enough space to clear one another. This will allow you to freely reposition the arm before tightening the knob and securing it back together again.