If you don't go the military aviation route (which fewer and fewer people are now doing), you generaly pay for you own training (which is quite expensive), and then work as a flight instructor at a local airport, possibly doing some charter work there, too, if possible. Hopefully, then on to a regional for a few more years before getting to the majors. A 4 college degree is helpful, but not completely neccesary, however some schools (purdue, UND, Embry Riddle), offer piloting programs that allow you to graduate with all of the flight training you need to start lying professionaly. If you stay focused and start early, becoming a pilot for the majors by your 30th B-day is a reasonable goal.
When in doubt, one B pump off