Your best bet is to go to a college close to you and take what ever Photography classes they offer. You have to learn to shoot on land before you shoot underwater as conditions underwater are way different than what you will find on land. If you don’t get good pictures on land first you will most likely not get good pictures underwater. Once that is done then look to people like Cathy Church or Stephen Frink, who are some of the top professionals in underwater photography and they usually have really good clinics that you can attend. Hope this helps!!