If your WordPress website is using Divi Builder this resource from Elegant Themes is a great starting point






To Edit A Page
 - Log into your website Admin Dashboard


 - Open Website in another tab (right click "Visit Site" link as per below)

 




- click Edit With Divi


The page will load it Edit Mode

 As the mouse cursor scrolls over the screen the following objects will appear that can be edited

 - Section (blue)

 - Row (green)

 - Module (grey) - modules include text, images etc

* You should only need to add / edit Rows or Modules


To Edit an existing Text module click the "Module Settings" icon as shown below






Once changes made - Click Save button to publish changes






Divi Demo tool to test adding sections, rows and modules to a page

https://demo.elegantthemes.com/?et_fb=1