Look into the US Power Squadron courses (http://www.usps.org/
You can take a basic boating course, and when you pass, are invited to become a member where you can take a host of other courses. Courses include piloting (navigation), seamanship, advanced piloting, electronics, engines, navigation (celestrial) and others. Where are you located and perhaps I can point you in the proper direction? Me, I'm a current member and have taken six of the courses. It's a volunteer organization which helps keep the costs low. And as a member, you can enjoy the functions and camaraderie of other boaters.
Good luck and be safe.