How can you contact publishing companies?

I'm only in Middle School right now, but I want to be an author. I know this might be something I'd have to really work at in terms of getting published, so i would like to try (to get published) when I'm 17 or 18. if you want an example of my work, I can send you something that won 2nd place in a creative writing contest. Anyway, my question is this, how would I contact those companies? I've gone to Razorbill, Speak, St.martin's press, Hyperion books, etc, and there is either no contact on or it "Won't accept unsolicited material". i know there are ways to publish online, but I don't like that idea, it's too easily stolen. And I don't want a lecture about how being a writer is unreasonable, I'm going to follow my dream or die trying(just kidding I won't die..but still) If anyone could help i would greatly appreciate it