I'm a big movie guy myself, which is why I am now an aspiring filmmaker. I too am in high school, 11th grade, and so I'm getting prepared for college and whatnot. I'm interested in some upper-tier film schools, and many of them require a portfolio of experience in the field. Not just interest, but ability and talent, and so I had to get myself a camera.
You should be asking yourself a few questions.
"What are you willing to spend on Independent Filmmaking?"
"Is this just a phase that I'll grow out of, or is it a dream I truly wish to pursue?"
"What exactly am I interested in? Editing? Being a cameraman? Director? Actor? Writer?"
The first thing I did was learned how to write a script, and although I'm kind lacking an idea for an affordable, in-my-house indie film, I'm aware of how to write a script. Download a program, such as "FinalDraft," which will automatically format your script, and learn how to write it.
When you've got a script, or while you're writing one, start researching cameras. When you reply to this post with a price range, I'll reply back with a few cameras that may interest you.
You also should get acquainted with some sort of editing, whether your experience comes from Final Cut Pro, Sony Vegas, or even Windows Movie Maker, you'll be on the right track because as long as you have some experience with editing, you'll get the picture much quicker in college or in the future.
Also, many people here would suggest just finding anything that moves and shooting it, my first film (that I filmed in about an hour and edited in like 20 minutes) was just of me making a peanutbutter and jelly sandwhich, and then freaking out that I spilled some excess jelly on the plate. Anything will do, as long as you get to know your camera.
So yeah, in 10th grade the best thing you can do is just get a camera and make a bunch of shorts for fun, stuff you can keep on the side just as experience in the field. In 11th, start researching some reasonable colleges you can apply and possibly attend that have Film Production / Cinematography as a major, and you should be set. Keep me updated with your endeavors!