How do you become a licensed contractor?

You have to work for a certain number of years in the trade, pass a business exam and a trade exam, pay the license fee, obtain a bond, and pay a yearly license renewal fee. This varies a little bit from state to state (in the US) but you get the general idea. When you apply, you will have to provide proof of your work experience. They take this very seriously, the references you supply WILL BE verified. If you falsify any information, you will be denied a license and may be barred from re-applying. Look in the phone book in your area for 'Registrar of Contractors' in the State Government listings. Call them, they usually have an information packet they can send out to you.