Im assuming you want to produce ebooks of your novels to sell, correct?
If so, the format you will be mostly dealing with is Mobi, both the Kindle Store and the Mobi Bookstore Take them. the program to Make Mobi Books is Called Mobi Pocket Creator.
it mostly depends on a Per Bookstore Basis.
the best place to start might be here
https://dtp.amazon.com/mn/signin
at Amazons Digital Text Platform.