If you want to publish your book, it can be done simply by creating a pdf document. You will need a pdf converter for this and there are free ones, like PrimoPDF. This is one simple way of doing it. Another way would be to host the book on a website, especially if it is fairly short.I have some free hosting if you like, which uses a c-panel and gives you 250 MB, without Ads. 

A few years ago, I wrote a short book on Psychiatric Astrology and now host that on a couple websites, namely my youtube channel and my Astrology blog. I simply put up a paypal button for people to donate to my favorite charity, which is India.

If you want people to pay for the book, then you will probably have to set up the paypal button to notify you when someone purchases the book and then it is automatically delivered via a link

.I am a lover of books and always love to have my library, and I don't think they will ever go out of fashion, but the last time I bought a book, I purchased it as a digital pdf download. It was 450 pages long, and I do have a laptop, so, for me, reading it was very comfortable. There is a new device, the Kindle, a wireless reading device for $359. That's certainly a choice, if you like.

Here's my website, Astrosynchronicity, and if you scroll down, you will see the link for the book. To open it, you will just need a free pdf reader like Foxit reader.