TMB, this is from wikihow to become a commercial airline pilot:
The best way to find out how to become an airline pilot is to ask an airline pilot. Know that it is a very long process, and, to qualify as a new-hire pilot at a major US airline, you’ll have to have a 4-year college degree (minimum), and years of flying experience . The highest quality pilot training is military training, but the commitment for active duty is long (up to 10 years), the competition for positions is intense, and the program is very demanding. Also, your service may entail serving in combat. To go the civilian route, expect to spend 5-10 years garnering enough flying experience in order to qualify. You must have a perfectly clean police record and must produce proof of citizenship. It is not a job for anyone who is not serious, motivated, and willing to suffer through a lot of intense training. Remember that the training does not stop once hired at the airline; pilots are tested by government-controlled, company-provided evaluations on a yearly scheduled basis, and also on a no-notice basis.