How does the Promail v.1.0 editor work?

Question

PHP

Good day, dear gurus!
Here I ran into the question of how this ( Promail v.1.0 ) miracle - Yudo works?

Actually, I'm interested in how sections, tags are added, content is edited, where it (content / page) is stored ...
Please do not beat with a shovel and do not refer to google.
And constructively explain or suggest what to read on this topic.
Thanks in advance!

Answer 1

promail.ma/envato/monitor/demo/layout2/js/main.js

Answer 2

Thank you! But how does it all work and where is it stored? Where does the layout go?!