I recently wrote this to someone who asked for advice on getting started with story publication. Thought it might be of interest!
1. Stop writing. No, not "stop writing forever." Just pause for a week so that you can spend your writing time learning about publication, so that when you *do* write you can write with publishers in mind.
2. Think about what you love to write. It sounds like you enjoy short stories-- but maybe articles can be interesting too? Nonfiction is much easier to get published, although fiction is by no means impossible. For now, I would write out 3 things that you love to write: say, "Girl stories" "Mysteries" "Articles about dogs."
3. Next, find magazines and/or contests. If you're writing a book, put that on hold because it's a whole different ballgame for short-term publication. In response to your original question, you can do BOTH. Publication is kind of like soccer, or any sport. You don't just learn one trick, you learn loads. The best way to find magazines is to a) go to the library and read some, or b) spend some time on Google, searching for "Young Writer's Guidelines." Innovative often spotlights different markets (a word for places that publish you) that publish young writers' work. I have some books to recommend that are "market guides", places that are literally lists of magazines that publish young wriers.
4. READ THE GUIDELINES. The worst mistake I see teen writers make (and one I've made myself) is just being SO excited about getting publish that they send just about any old story to any old magazine, without being smart. Would you submit your science project to your history teacher? Nope (or you'll get an F.) Treat publishing like a "match" card game: match a story or article to a publication. This might seem abstract, but it's not. If you've written a girl mystery, and you find a magazine that says: "We love mysteries with girls," then that's a match.
5. FOLLOW THE GUIDELINES. Again, big mistake if you don't. Magazines will tell you what information to send (your age, email address, things like that) or whether to email it or mail it, etc. READ THEM AND FOLLOW THEM.
6. Make a plan for the long run. This last tip is something I'll be covering in the new year for Innovative so I'm not going to write much about it now. I've been published about twenty times, in both really small magazines and big ones that have paid me almost $200 for an article-- and I'm still in high school. You *can* do it, just be patient and be smart about it. If you have any more questions, please feel free to email me.
Off the top of my head, here are some zines to look at (that publish young writers' fiction):
Stories for Children (www.storiesforchildren.tripod.com) publishes stories *for* kids age 3-12 but accept pieces *by* kids up to age 17. They don't pay but are always looking for young writers to write (better chance of getting published.)
New Moon: Magazine for Girls and their Dreams (www.newmoon.org) publishes fiction and articles by girls up to age 14. They pay .06-.12 cents a word, but it's competitive.
ChixLIT (www.chixlit.com): I would *REALLY* encourage you to submit a piece to them. It's a very small magazine, and you don't get paid, but then you will be PUBLISHED and that always helps when you submit to bigger magazines. They publish loads of stories and articles by girls ages 7-17.