Get a bucket full of hot water, a chair and place the bucket half full of hot water in front of the chair. Now, sit and ask somebody to cover you with two or three blankets.
The objective is to inhale the vapour in a confine environment, and making sure that the heat goes into both your nose or breathing system and skin. That exercise will take a minimum of thirty minutes.
One will know if one is done when one is sweating all over the place like a donkey.
Your nose may be running (literally), or one may be yawning like a lion repeatedly. After all that, one can feel asleep or tired. Those are good signs.
Please note that this is a sauna. One can do that once a week for at least two months. The ultimate aim is to clean your breathing system, and get rid of all dirt in your skin.
Get a doctor approval before doing it.
Stop right away if you feel uncomfortable.
You do not have to do it if you do not want to.
Most importantly, do not burn yourself with the hot water. If you are likely to fall into the hot water then ask someone to help or supervise you. Do not do it without your parents' permission if you are a teenager or child.
All good? Best of luck.