This article is not going to be directly about the Divi theme, but about learning some coding. Basic knowledge of HTML and CSS will help you to tweak Divi so that it fits your needs. You will be able to perform some small (maybe not even small) customizations to not just Divi theme, but to any other WordPress theme, or even to an HTML/CSS template.
I’m writing this article from my own experience. I was a little stubborn and I thought I really do not need to know HTML and CSS. I knew just some very basic stuff like how to make a hyperlink or how to insert an image and center it, etc. However, I knew hardly anything about CSS classes and IDs and similar stuff. I thought that if I know how to use WordPress and the Divi builder, I will not need any coding skills at all. Yes, it’s true that you can build a nice website with Divi without any programming knowledge, but knowing at least some HTML & CSS basics will help you with customizations. When reading a certain article on the Elegant Themes blog I found out about CodeAcademy. They offer some free and really nice HTML & CSS courses. So I decided to take these courses and I can say that it has already helped me with creating some Divi websites for my clients. So if you are more a designer than a programmer, like I am, I recommend you to take the CodeAcademy course and learn HTML & CSS basics with it. You won’t regret it. And don’t worry, the whole tutorial is written in a nice interactive way.
Another good website for learning HTML and CSS is W3Schools. You can try this one, too. I have not tried this website yet.