Even though I can't tell you how to be a writer, maybe I can give you some
Do a lot of reading. Study the style of a lot of authors you admire but do not
try to copy their style. You will have to find a style of your own. Write in a
way that is natural for you.
Read all the books you can find on creative writing. Your librarian can help
you find books that will help you.
Do not wait to start writing. You are never too young to start. Your first
story should be based on something you know well. Make it exciting. Do not
worry about grammar and punctuation on your first draft. The important thing is
to get the story down on paper. It will probably need a lot of revising and
rewriting. You can worry about grammar and punctuation then. Remember, the more
you write, the better you will be.
Don't get discouraged. If you can keep trying and don't give up, you will make
it some day. The road can be rough but the day you see your work in print makes
it all worth it.
Best of luck!