To engage the arm, lift it straight up to disengage the locking detent then rotate it until it is in the 90 degree position then slide it into the housing until it stops.
Grab the safety hook. Insert safety hook into hole at the end of the arm from front to back.
With safety hook engaged, you can now use your LadderGadget.
To disengage and store arm for travel, simply remove the safety hook and slide arm slightly out of the housing until you can slowly lower it into the travel position.
Once in the travel position the arm automatically locks into place. The safety hook can hang freely or be inserted it into one of the holes in the arm for travel.