Develop the story you want to tell. Regardless of being in prison, the rules of telling a good story still apply. You want to make sure you have a story, whether fiction or nonfiction, that publishers will want to buy. Here's the catch. The "Son of Sam" law, created in the 1970s after the arrest of David Berkowitz, states that no convicted criminal is allowed to profit from his crime by selling his story to a publisher. Your story cannot be based upon your crime.
Write your story just like any writer would, using whatever tools are available to you. Being in prison, you may be limited. If you have access to a computer and printer, so much the better. If not, try and get a typewriter. If you need to, write with pencil and legal pads, which almost every prison allows. Get your story on paper in whatever way you can. If you have to write it by hand, send it outside to a friend or family member and have him type from your handwritten manuscript.
Get a current copy of "The Writer's Market." If your prison has a library, see if the book is there. Unless your prison keeps an updated library, odds are it won't be. Someone outside of prison will need to bring you a current copy. This book is essential for any writer seeking a publishing deal. It lists publisher guidelines, including the type of work each publisher accepts, how to format your manuscript and where to send the manuscript. It also tells you how much you will be paid, and how long you should wait before inquiring about your submission.
Give your manuscript to a family member if you can't send large manuscripts out from your prison. Your friend or family member can go through the submission process for you. As a prisoner, you can publish books, as long as the books aren't based on any crime you've committed.
Write a query letter to include with your submission. The letter should be brief. Introduce yourself in the first paragraph, be honest about where you are (it could work for you or against you) and provide a synopsis of your story. Sign the letter and include contact information. Include this letter with your submission.