For aspiring writers, my best word of advice is to write as often as possible, and finish whatever you are writing, whether it be short-story or novel, before moving on to the next project. You learn a lot by taking a project through from beginning to end.
Classes are available at local writing guilds, community colleges, and universities. Some writer's groups--like The Romance Writers of America, of which I am a Charter Member, do not require you to be published when you join, and they have lots and lots of information on the how-to's as well as the business of writing, available to their members.
If you aren't interested in joining a group, or do not have one near you, you can still teach yourself the writing craft, just as I did, by reading everything you can get your hands on. Writer's Digest Books publishes many books on all different topics. I have many of them in my personal library. TECHNIQUES OF THE SELLING WRITER, by Dwight V. Swain, University of Oklahoma press, is perhaps my favorite how-to-write book. You should also read as much as possible in the genree you wish to be published--romance, mystery, western, etc.
When you have a project ready to submit for possible publication, the reference librarian at your local library can help you find the names and addresses of publishers in The Literary Marketplace. The most important piece of advice I have is to keep going. If you are a writer, if the stories keep coming, even when you try and shut them off, then keep writing, keep submitting, keep learning, and don't stop believing in yourself. Writing is a craft, like any other art. It takes time to develop it, but it's well worth the effort, the first time you see your work in print.