I just graduated from high school and now have about three months off. I want to use this time productively and learn more about music theory and composition so I can help this site out by making arrangements. Where are some good places to study it online? I've been using musictheory.net, but I was hoping to find something less boring and more fun. Thanks guys.
Just arrange. I've never taken an actual theory class, but I can tell you quite a bit. That's mostly because I studied the piece. All theory really does is give definitions to what a specific thing is. It doesn't tell how to compose/arrange.
you could try out this video series on youtube
http://www.youtube.com/user/Lypur#grid/user/B585CE43B02669C3