Question about my future?

look, i'm about to enter high school, and over the years, ive really been looking at some careers that i think would be interesting. out of all these, i chose a pilot. preferably, i would like to fly for southwest or delta airlines. i want to know what path i should take from here. what are the basic requirements for a pilot? what classes should i take? what should i do when i have job shadowing? would the air force be a good step? when they give me a job interview in the future, what would they expect? i would appreciate a good answer with a lot of explanation. thank you