Is there a manual I can read how to join NASA

NASA itself or one of its contractors ?
Probably best to figure out what area you want to work in and investigate from there.

Nasa.gov or USAjobs.gov would probably be your best bets.

https://www.nasa.gov/audience/forstudents/careers/index.html

Nasa only takes educated people though.

get a PhD and work with them

If you want to do the actual work, be a contractor. The federal employees are mostly lazy and dumb and push red tape all day (as with most agencies in the Government).