How to control water pressure with a throttle?

i want to try to make a jetpack that can allow me to just cruise around in my backyard a couple feet up (im 13 and want to become an engineer). i was thinking to use pressurized water in a tank or thick pipe to propel me into the air. Is there a way i can do this and use a throttle to control the amount of water that shoots out? Such as if the throttle is not being pulled, no water comes out, but as i pull it water starts to jet out and slowly propel me into the air. please be detailed and tell me anything i would need. maybe if you can even link to diagrams or anything. I just need some help haha 10 points best answer!