Thank you both for replying!
Wow-this seems like it's going to be much harder than I anticipated, and you're right, Monarcheon, I didn't understand half of your critiques. My main reason for going to college for composition is to learn this stuff--but I'm finding out more and more you basically have to be an expert before you can even get in (which seems like a catch-22, in my opinion)! Is there anything I can do to learn some of this information and apply it to my pieces before I attempt college? One thing I do know is that music is my passion, and I'm not about to give up when I've barely started just because I don't know how to do it. (By the way, some of the critiques that I did understand are not really in my control because I don't know how to fix it in MuseScore. My handwritten copy doesn't have some of the things that you pointed out. And some of the left-hand notes are meant to be an octave lower, I just forgot to put that in there.)
Maarten Bauer, I was thinking of six different colleges: Oberlin (the hardest to get into, I know), Whitworth University, Biola University, Liberty University, Texas Christian College, and Belmont University. I am not financially able to visit any except a slight chance at visiting Whitworth. Also, I have been researching this for a long time and I have heard that it's almost impossible to make a living out of composing, but I've also read that the only ones who manage to make it work are the ones that hang their entire career on composition with no plan B. I'm not saying that I honestly have no plan B--I have very good grades and I could do virtually anything--but film music is the only thing I'm really passionate about.
Do either of you have suggestions on how to turn these ideas into something good enough to submit?