How to become a license contractor?

Ok I have tried to google this but I can't seem to find anything on how to become a licensed contractor. I have done a few DIY projects growing up, building decks, patios, demo, likes of designs and crafts... I know that I am far from being a professional contractor and I wouldn't try to work on anyone's house with the experience I have, but I want to know how to go about LEARNING more of the actual building and crafting that goes with contracting. I heard there isn't much schooling for it but i don't know of any other way to learn. I plan on asking different contractors around where i live if they would like a part time worker for the summer or even a volunteer just so i can learn more. I am asking anyone who is a contractor how they become it. How did you learn all the stuff you know. I know i want to specialized in bathrooms and kitchens, or landscaping. I see all the shows on DIY like bathtastic, yard crashers...I want to know how to become those guys. Please any help would be amazing cause i am really stuck on this. Thanks