Last week I showed you how to create a child theme with the use of a plugin. That tutorial was simply a one click install solution which gives you a new header, footer php files and a blank CSS sheet and I in the post I demonstrate what happens if you don’t use a Child Theme and update your core files (example when Divi moves from 2.4 to 2.5 or 2.5.1).
As I have said before the term Child Theme has broad implications, I would define them in this way:
Child Theme: simply a duplicate of your blank website which you create before you begin your web design project. Creating one will save you from recreating site customizations to your header, footer and CSS if you update the theme.
Premium Child Theme: A Child Theme that you pay for, which comes with fully designed pages, posts, and design customizations that simply needs your images and copy and other minor tweaks. These are found in the Elegant Marketplace Shop.
you don't show how did you get the zip file though