What kind of background and education is necessary in order to write and sell books in the field of computer programming?

Now the deal with programming books is that the depend on you mastering the language and then being able to communicate how someone else might master the language.  This is quite a bit different than being enormously masterful at programming in this language. Each programmer develops their own style, often other programmers will burn down the code of a predecessor and rewrite it once they become responsible for that code, not because they are jack-asses, but because reading someone else's code forces you into their mind and if you don't think like them, you will waste much time trying to maintain the code, and worse it is almost impossible to really improve it.  Creating a specification and re-writing gains you the ownership of the code and thus you can maintain and manage it more efficiently. Many books on programming concentrate on just exposing the various elements of the language and providing basic "seemingly obvious" examples to to new users.  Of course, these people don't at all see all of these examples as obvious at all. So, first and foremost, study the competition.  What books sell what books die. Read both.  Find what succeeds and do that.  You need to have a sufficient command of the English language to be able to write clearly.   And you need to keep to a high school level regardless if you think you are talking to college graduates.    You need an editor.  If you intend to write books for distribution by major publishing houses, you need an agent. There are many paths today to create and sell "books" via outfits like http://Udemy.com And you can can self-publish ebooks on Amazon or iTunes. So, the next deal is marketing.  If you build it, they will completely ignore it unless you tell folks about it. So, you need to study marketing.  You need to know past what sells, how to sell it and where to sell it and how to get people to go looking where you sell it for it. The Public Library is your friend.  GO, graze the bookshelves and find the how to guides that speak to you.  Then you assemble the tools and begin outlining and building the examples and resources that you will share with your readers to make it worth their time. Writing a book is one heck of a job.  Don't quit your day job until you have enough writing revue to cover twice your yearly expenses.  Your problem will always be the next book, if you plan to do this professionally. But, understand, it is easier to be elected to Congress than to be a successful Software Book writer.  Just think about that.  And, Congress pays better. Good luck.

Publishers don't care about author credentials except as they help market a book. If your book will sell, they'll publish it. If people find it useful, it will sell. If the publisher doesn't believe it will sell but you do, then publish it yourself. The people who make a difference in the world are not those who ask permission, or ask whether they are qualified. Just do it.