I started writing a book at the end of my 5th grade year. My 6th grade teacher is totally against teen authors, so I stopped for a while. Then my 7th grade teacher inspired me to start again. I'm 13 and I wrote many short stories (all turned down by my teacher last year) but this is my first chapter book ever. I need a publisher but I don't know where to find one.
If you are in the US you could consult Writer's Market 2016 for names and addresses of publishers and advice to authors. For the UK and Commonwealth countries a similar guide is the Writers' and Artists' Yearbook 2016. These two annual guides for authors are the most well known but there are other good books on the same lines as well, and I expect the same is true for other countries.
Be warned that it is very difficult for a first time author of fiction to be published. There is intense competition. However the internet has made it far easier than before to find an audience if you don't mind not getting paid. It is also possible to publish your own book electronically, although doing this does cost quite a lot. If you search this site using the tags "self-publishing" and "ebook" you will find more information on that subject.
I hope you don't mind that I made an edit to your post, correcting a word that was used wrongly. That does bring up an important point: in order to be taken seriously by a publisher it is very important to thoroughly check your work for incorrect use of English.
I would suggest submitting your book to young author competitions, both locally and nationally. And win. Otherwise, don't give up and keep doing it. You have a tiny chance at a commercial publication if you win an award--unless your dad owns Random House--in which case you're golden. Can I get his number?
You really need an agent first, very view publishing houses will even look at unsolicited manuscripts that an agent hasn't recommended to them. Try looking at http://agentquery.com/. You can search for agents that handle your genre, then write up a query and send it to them.
For fiction you need to have a finished work before you start shopping for an agent generally. Also make sure you get your work edited.
Worst comes to worst you can just self-publish through lulu.com or amazon or a dozen other sources.