First step is to loosen the pinch bolts on the side. Turn it counter clock wise. An easy rule to remember is, “Lefty Loosey, Righty Tighty.”
Then tighten the bolt on the top cap clock wise. But make sure you don’t ever tighten it or else it will compress the bearings making it hard to turn your handle bar.
Once you’ve got it at the right tension, simply tighten the pinch bolts and go out for a ride.