This lesson will answer your questions. There is a mini-quiz at the end of the lesson. Before you start to write fiction for money, you must realize that the material must be good enough that someone would want to pay for the chance to read it. A book publisher is taking a risk of spending a considerable amount of money to publish a piece of fiction that may not sell. So, your material must be good and have value before someone will take a chance at spending money to publish it.
Most fiction writers are independent or freelance.
Buyers of fiction typically include magazines, book publishers and movie studios. There are also some new Internet options where you can sell your fiction. Some writers have tried self-publishing books or pamphlets. Poets have been the most successful in this method. I don't know of any self-published fictional books that have made money.