Novelists teach. Poets teach. Journalists, short story authors, and bloggers teach. All teach creative writing courses. Some are published and well-known, and others are known more in literary circles.
I've taken 3: one almost 20 years ago, one about 5 years ago, and one 3 years ago. Each teacher was wonderful, and each helped me write what I wanted to write. All three of my courses were in person, but I understand that there are some online creative writing courses like the Gotham Writer's Workshop (http://www.writingclasses.com/).
You also might try a local community college or university. Sometimes famous writers are "hiding" out in your town just teaching away...
It's better to take a creative writing course than not to. At least the class will provide some structure and give you deadlines to work around. Some teachers or professors allow you to read aloud, or if they recognize that you're shy, they'll work with you quietly.
You could teach yourself, too, by reading writers magazines like "The Writer" and "Writer's Digest," and books with writing exercises in them. Some exercises you do are so good that even if you do the same exercise twice--6 months apart--you'll end up with 2 very different pieces of work.
Don't forget to check out the writing and publishing section of your local bookstore. If cost is an issue, take a notebook or journal with you and take notes.
See who published your favorite books, whether fiction or nonfiction. Find that publisher's website, and see if that publisher also publishes writing guides.
Best wishes!