Advances in technology have made self-publishing a viable and exciting option for budding writers. There's now no need to go through the old-school process of literary agents and publishing houses, but instead put your product out there, directly to your audience. For those wanting to end-up with a real, tangible book, the route is print-on-demand. In the past, self-publishing in this way would have meant speculatively ordering a large number of books (since this would traditionally reduce the cost per book and help keep costs down) and then hope to promote the title yourself, meaning the very real possibility of losing quite a lot of money. Nowadays, sites such as Lulu.com, Smashwords and Creatspace offer the possibility of printing-on-demand. This means that fulfilling even an order of one solitary copy of a book is perfectly viable (technologically speaking), and so your title can just sit waiting to be demanded by your audience. It's a very pure model of supply and demand; the electronic file containing your book and book covers sits on their hard drive. When it's demanded, they supply. The question of how much Lulu (for example) charge per copy always comes up in conversation about print-on-demand, and it's a lot simpler than you might imagine. When your file is uploaded and decisions about the type of paper and size are made, Lulu.com then tell you how much each book would take to produce. You then set the cover price, bearing in mind that anything over and above the production cost is your share. Pricing is a tricky business. People won't pay megabucks for an unknown writer's work, but price it too low and of course you're reducing your profit.
Another option for writers is to produce an e-book. There's an immediacy about e-books and a thril at the prospect of global readers being able to download and read your work. The process for creating one is very similar to the print-on-demand, but - with Amazon KDP at least - much easier. I can't comment on other e-book creators simply because i haven't used their services. There are a multitude of e-book readers such as Kindle and Kobo, but don't forget that people can also read e-books on smartphones and tablet PCs, iPads and the like. There's a growing market out there, and many aspiring writers are getting onboard at this thrilling time.
I used Lulu.com to publish my first book, Born in Mid-Air. I found it fairly straightforward to use with a decent end product and excellent delivery times. One thing which I'd recommend is to set-up a 'dummy' project and practise formatting and uploading files and cover images. Only when you're more comfortable with this would I start your proper project. There are other publishing/print-on-demand sites available such as Smashwords and Createspace with various 'pros and cons' for each. I won't comment on them here since I have no experience of using them. I'd recommend shopping around before committing to any of them, reading user feedback and so on, and making sure they do what you need them to do.
Amazon KDP is a site where you can upload book content and cover images and convert them into a file that becomes a Kindle edition which can be bought on Amazon. I used it to create the Kindle editions of Born in Mid-Air and my comedy script, Sticks & Stones. Amazon KDP is amazingly simple to use, and even offers a downloadable guide for you to read offline explaining the various terms and processes. The ease of use can be a downfall, though, as I initially felt a surge of excitement and impatience. I'd really recommend taking your time and not rushing into anything. Once the files are in place the process (in terms of pricing) is very simple and similar to print-on-demand.