The company that produces the Divi WordPress Page Builder, Elegant Themes, has just revamped their documentation on the product and put out a lot of new training material including videos on how to learn the ins-and-outs of Divi.
In the coming months they will be integrating these tutorials right into the Divi Builder so you can access the videos and help information right from your site.
You can check out these resources on their site or YouTube Channel