As a freshman you have three choices that I can think of ...
1) make movies with your friends that do not require a budget in the hopes that you can demonstrate enough skill and discipline that someone will trust you with their money.
2) get money from friends and relatives who are willing to risk their money because they like you and want to support you (unless you've got a rich uncle, this probably won't get you too far)
3) find someone (a production company, etc.) who is making movies and sign on to crew with them; for free, if necessary. You still won't have money, but when you're older and you can get funding for your movie idea, you'll have the experience to make good use of your budget. Also, if the people you are working with like you and your idea, maybe they will help you produce it.
Have you read anything about what Clive has been saying about writer/directors? If you really have a good story, work on that script for a year or two until is is really polished, get it copyrighted and ship it around. Making a low budget movie can still cost hundreds of thousands of dollars. If you can sell your script, you can get some money and prestige without raising a million dollars and trying to do it all yourself.
If you want to make practice movies while you're working on your really big idea, go back to option #1 above. Get an inexpensive camera and work with a group of your friends to develop some original movie shorts that will help you get experience that will be invaluable if you ever tackle that big project on your own.
sorry for rambling; there is no limit to what you can do, but you must walk before your run (I know, I probably sound like your dad

)
Doug