You're 16. At this point in life, you probably know nothing of anything, or pretty close to it. So you need to fix that. Learn.
This doesn't have to be schoolwork. Go to the library and just browse around until you see a book title that interests you, then open it and see what it's about. Go out in your free time and explore the world around you. Search keywords on google or wikipedia and follow in-article links around. When you see other people doing things you don't recognize or understand, politely ask them if you can have a few minutes of their time, then ask them about what they're up to, find out what they're doing and how you get into that. Accumulate friends and associates who know more than you do, and talk with them regularly about what's going on in their lives.
Stuff your brain with as much new knowledge as you can get into it, even the most random and seemingly-pointless stuff. Get an idea of what's out there in the big bad world, what life has to offer. Sooner or later, you will probably discover something that piques your interest. Once you find it, take steps to do it, be it, understand it, or spend time with it. This will probably involve more learning, but now it should be focused and directed toward something you like.