This is a pretty advanced tool so you should seek out some help if you have limited experience with EPUB standards. (edwardsbrothersmalloy.com)
It won't help you write your novel or show you how to build out your characters but it will help you comply with recent EPUB standards for eBooks. (edwardsbrothersmalloy.com)
First, there is an industry - wide ePub standard. (darcypattison.com)