Creating your own Ebook is quite an easy exercise, and in recent times I have created 3 ebooks covering various aspects of my historical family records, plus this one that records a visit to Europe to see a stage of the Tour de France in 2015
The main text of an ebook is written in HTML, which is the same language that is used on all web pages, but you do not need to be concerned about this, because the source text can be written in MS-Word (or any other text editor) and a software package can then be used to convert it into unfiltered HTML files for inclusion in the ebook.
There are lots of software packages available that are easy to follow, and which create excellent results. I use Sigil which is a free package only 27mb in size which creates ebooks in the "epub" format. These ebooks can easily be converted to various other formats using Calibre.