Get involved and get your work out there (practice practice practice!). In my high school they had photography and digital photography courses as part of the art department and that teacher was a huge resource for me as far as improving my photography went. If your HS doesn't have anything like that I'd talk to any sort of resource you can find (HS art teacher, any professional photographers in the area, college arts department, etc). Read lots of books, take lots of pictures, enter contests, and don't be discouraged. I decided to move away from the arts as my education went on (it's another fun hobby for me) but that should give you an idea of how you want to move forward with it. Digital photography was one of my favorite classes (and all I used was a dinky point n shoot digital camera)