Divi comes with a very comprehensive documentation which was overhauled in mid 2017
The Divi theme documentation is quite extensive and well thought out to give you an easy introduction to the theme and a detailed explanation of its various elements. The main Divi theme documentation page lists The Divi Basics, The Modules, Additional Features and many tutorials for everything Divi.
The official Divi documentation should help you get all the info you need to use the theme, but if you need more help than what is available in there you can check out the excellent Elegant themes support forums and new live chat support, or in one of the many helpful FB groups for Divi users.
Divi documentation & help overhaul
Im mid 2017 the documentation was given a large refresh to include new features, video intros and better explanations of features. You can browse and search all of the documentation on the Elegant Themes site or access many via the Divi builder itself. While Divi is a pretty intuitive page builder to use and nobody likes to read the instructions, spending a bit of time in the Divi documentation before you start building you will make the process a lot easier.