How can I fix my handlebars?

I just got a new bike. It is a mongoose boys 20 inch orbit. It has this rotor on the handlebars that allows you to spin them without turning the wheel for tricks. It should be able to stay stable or in position. I don't know how to lock it and unlock it. I want to make it stay in position. How do I do this?

Use a hammer! It is an all-around fix it tool. Use it on your computer, tv, car, jehovah-witnesses, getting a raise at work, garage doors, bikes.....etc.

unscrew to change the position then tighten

you cannnot stop this without buying another part

You have a misunderstanding as to what the rotor is supposed to do.

The purpose of the rotor is to allow the handlebars to be spun, without tangling the brake cable.

It has nothing to do with whether the wheels are turning or not.

You're rather confused. The rotor just stops the cables becoming tangled. The headset and fork are very much a solid item.

If your handle bars are moving and your fork is not, something is wrong. It has nothing to do with the part you refer to, as others have answered it's only so your cables don't get twisted. Check the tightness of your headset.