This is one of those subjects that you read a lot about. Of course, I am only dealing with my area of writing a book of fiction, not technical manuals or any other non-fictional books, although their process might not be too different. When you write e-books, there is little to no cost involved, but what happens when you want to turn your fiction into a hard copy for those folks who don't want to read a story online?
In my experience, Amazon is surging ahead in finding a way to help the average writer by joining up with CreateSpace - an online publishing company that is amazingly user-friendly. Once you have worked your story in a simple software like Microsoft Word, gone over it a few times to make sure your spelling and grammar is perfect, have an editor look it over or another person who has a good handle on grammar and word usage, format it according to their directions, you are ready to prepare it for uploading. This involves sizing it to fit the size book you want, saving it as a pdf and then uploading it to their site.
Once they receive the document, you let them review it through their automated process and then have a look at your book on their site to make sure you like it. They have more decisions that you need to make, like where you want to market it and other details. For almost nothing, your book will be ready to print - although the price will be a little higher than a mass produced book since they need to recoup their costs from somewhere.
If you have used another site, feel free to comment.