With the pin tool holding the adjustable cup in place, presumably with your left hand, lock the adjustable cup in place by tightening the lockring (turning clockwise) with your right hand. Stick the hooks into the notches and crank tight. Really snug it up. Expect the tool to slip off now and then, because it’s a tenuous connection, but you’ll get the hang of it, and no complaining. Every bike mechanic who works on this style of bottom bracket has slipped the lockring wrench off.
There are better lockring wrenches, but this one is absolutely up to the task, and costs only $6. If you are groovy enough to take on a cup-and-cone bottom bracket in the first place, consider this part of the classic experience. Later on, if you want to get a more secure tool, you can pay four to twelve times as much and do that. But you should earn your way there first, by suffering though with this perfectly adequate one from your trusted pals at Hobson-Zingo.