First unscrew the 2 star head screws on the plastic swivel cover to expose the headset. Then make sure the top nut (locknut) and any locking nuts beneath it, are loose. Then you thread the cone (bottom nut) clockwise until it stops using only your hand or light pressure if you’re using a spanner.

Then, you tighten the top nut against the cone (bottom nut). Next, you turn the fork slowly to feel how smoothly it turns and you push and pull on the fork to feel for play (there should be no play). If it feels right, you put a spanner on the cone (bottom nut) and another spanner on the top nut and you turn the cone (bottom nut) counterclockwise while turning the top nut clockwise to tighten your adjustment securely. The parts shouldn’t move much if at all. You’re just locking the adjustment so it won’t change when you’re riding.

Sometimes you have to try a few times to end up with the right adjustment because securely tightening the nuts against each other will effect the bearing adjustment. But, within a few tries you should be able to make a nice adjustment. When refitting the swivel cover make sure that the 2 star head screws are screwed on the existing thread, if the screw is forced over the existing thread there is a possibility that the screw can shear in half .