So you are a young writer...

There is a whole community out there of teens like you, and you should have no problem publishing your manuscript if it is well written. Being a teen writer is actually a benefit because young authors are good publicity for publishers. Don't get discouraged, there are many published adults who are terrible writers. 
Your writing will improve with age and practice. I started my first novel when I was 13. It was terrible, so then I tried writing a screenplay, again, that was cliche and it makes me throw up inside my mouth just thinking about it. I have some hope for my novel Hudson by the Day, but if it doesn't work out, I can always start again with a new novel. The writing process isn't about finishing a novel, it is about becoming a better writer, so hang in there. 
Enter contest, and make a name for yourself, Keep writing, and don't let adults tell you what you can or can't do. That is all it takes to become a teen writer. Our generation has a 50% chance of living until we are 100 so there is lots of time for us to write that novel, and another novel, and another novel.

What to do about adults

My parents were worried when I told them I would be writing yet another novel. I had to promise them that I would spend non writing time with them, if they would let me write in peace. Make sure your parents know what is going on. Your novel might seem personal now, but your parents might be your best editors. Never let an adult discourage you.

Skeptical people

Some people think that kids can't write. Ignore them. It is up to you to prove them wrong.
see this link
Some adults think that teens are unable to be creative and come up with original ideas. (look at Eragon) Don't be a parrot, and find your original idea.

Young writers just like you

  • Mary Shelly wrote the first ever science fiction novel, Frankenstein, when she was only 19. 
  • Anne Frank's Diary is called the "voice of the war", unfortunately she was killed in a concentration camp before she could see it published. She started writing in it when she was 14.
  • S.E Hinton's novel "The Outsiders" gave her the title, the messenger of the youth.
  • There are many more teen authors out there, and your name may soon be one