Write your story out into a brief one-to-two-page synopsis, which tells who the main characters are, what the basic premise (problem, struggle and resolution) is and shows off the tone of the film. Register this document with the Writers Guild of America so it is protected. Registration costs $20 and is good for five years.
Write a query letter to producers with a one-to-two sentence logline and a couple of paragraphs as to why you're submitting it, your personal background and any other important relevant details.
Go through the listing of producers and read which ones are looking for stories in the same genre as yours. "Fade In" magazine offers a great directory of producers, which is updated three times a year. Create a list and mail or email your query letter and synopsis to all of these producers.
Wait for a phone call, email or letter requesting a meeting. If you do get a response, it can take weeks or even months. Typically, if regular postal mail is used, any response will take at least two to three weeks. If you've used email, it may take up to a week after sending out your query to receive a response. Expect to hear back from around 10 percent of your submissions if you have a decent idea, more if your idea is stellar and your query letter is spectacular. If you do have someone email or call you with interest in reading more or meeting with you, arrange a meeting. Prepare for the meeting by making sure you have the story rock solid and will be able to answer any questions the producer might have. If the producer shows interest in your story and wants to make an offer immediately, call an agent. You can find lists of agencies online or in one of the guides published by "Fade In" magazine.
Sign an agreement with an agent or manager. Agents typically receive 10 percent of any money you make selling your work and managers make 15 percent of your paycheck. The agent will negotiate your contract to get you the best deal for your true story. This can take weeks or months to finalize if it gets to the actual negotiation stage. The chances of having a script bought are extremely low, but you should continue to persevere and try to get your story sold. Sometimes it just takes a lot of patience and some good-old fashioned luck to make things happen. If it does, sign the contract with the production company.