Everyone can write. Everyone can run.
It's true. However (yeah, you know where I'm going), just as not anyone can run a marathon, not everyone has a gift to write clear, lyrical prose that entertains and engages readers. That's why you need to treat writing just as you would any other sport.
You need to get up each day and practice. And just as with running, you will need to warm up, stretch and find inspiration. A running partner can help, too.
I have a friend who runs. She runs every day. She runs because it makes her happy, keeps her healthy and because it feels good. Whenever she can, she enters a mini marathon or fundraiser run. When I asked her why she does it, she said, "It's fun, and it makes me a better runner." When she runs these races, she runs to win. She doesn't train extra for them, but she makes sure she's prepared to go the distance.
Such is true for writing. You need to make writing a routine, and you need occasional "races" that are fun to be part of and make you a better writer. Go ahead, challenge yourself. Brave yourself for some feedback, even some criticism. Believe me, it will make you better at what you do.
If you are a teen writer, here are some places to submit your work. Be sure to read their submission guidelines.
New Moon Girls - online and paper; girls ages 8 - 14; accepts poems, articles, stories.
One Teen Story - online and paper; publishes stories for the teen audience.
Teen Ink - online and paper; teen audience and writers; publishes fiction, nonfiction, poetry, photos, art.
The Writing Conference Contest - once yearly; open to students in elementary, junior high, high school; accepts poems, narratives, essays.
Oh, and don't forget the ThisGirl summer writing contests!
After you've viewed the above sites, set a target. Plan to submit at least one piece of writing by the end of the year. In the mean time, practice.
Please post links to any of your work online, or just give a personal shout out for your achievements. Good luck. Write on!