Kazze,
The first thing you need to be a filmmaker is desire. Desire is what will motivate you and drive you to pick up the camera and shoot things. You obviously already have that, so, you're already a filmmaker.
Filmmaking is a large amount of things that come together, and is an amalgamation of the technical and creative. By that I mean, for instance:
Lighting can be technical. A three point set up so you have your key, fill, and kicker light. Alright, so you know how to light a subject now, where to place the lights for good effects, but it's also creative. How far away should the fill be? Should the key be higher or lower to accent the shadows on the face?
Don't let filmmaking seem daunting to you -- anyone can do it. The biggest thing, and I can't stress this enough, is a good script to shoot. Something creative, something that stirs the imagination... something controversial. Don't be afraid to write something because you think people might be offended. Offend people.
Things like lighting, setting up the camera, editing, you can pick that up pretty easy by just practicing and flipping through a few books, and reading this forum.
Now, your question was how to get started. That's simple.
Pick up a camera, and start shooting. Shoot anything and everything. Get your friends to come act out a short scene for you. Record yourself staring at the camera. Do anything. Don't get caught up in sitting around reading books or technical manuals, actually start filming things -- you'll be surprised at your results.
I hope you find this helpful.