I am currently 17 years old and next year I will be graduating from high school. My plan is to go to the Air force and become a Tactical Aircraft Mechanic. Obviously I am going to go through BMT and then Tech school. But after I learn that career I want to work at an Airline. How does that work specifically?
This answer assumes you intend to join the US Air Force and seek certification as a mechanic with the US FAA.
I would suggest you keep a personal log of all your training and all the work that you do while in the Air Force. This, along with your service record, can then be used as evidence to support an application to the FAA to be allowed to take the exams for the Airframe and Powerplant Mechanic (A&P) that will allow you to seek work with airlines. You take three exams -- General, Airframe and Powerplant, then an oral and practical exam with a Designated Examiner. If you pass all of that, you are issued your license as a mechanic and off you go!