To be a pilot, you first have to go to commercial pilot ground school. You have to fly at least 250 hours; then you have to pass a written test. To get your certificate and look for a job as a pilot, you also have to pass a check-ride. This is like a driving test to get a license, only for a plane. An examiner asks questions, and the pilot-to-be has to plan a flight and fly with the examiner.
Once you pass the test, you get the pilot’s certificate. Next you need to pass a medical examination. You also have to take a test in flying with certain instruments in bad weather conditions. If you want to pilot a plane with more than one engine, like most commercial airplanes, you need to take even more lessons and another check-ride. Finally, you need a lot more experience flying to work for a commercial airline.