A child theme inherits the look and feel of the parent theme and all of its functions, but can be used to make modifications to any part of the theme. In this way, customizations are kept separate from the parent theme’s files. Using a child theme lets you upgrade the parent theme without affecting the customizations you’ve made to your site.
Read more about this on wordpress.org developer guide.
If you want to modify some parts of the theme, use a Proteo child theme is highly recommended.
Once you have download the theme, you can install it by following these instructions:
- Extract the folder inside the .zip downloaded file.
- Upload the extracted folder to the /wp-content/themes/ dir on your server via FTP.
- Activate YITH Proteo Child from the Appearance > Themes screen in your dashboard.
Please note that Proteo theme must be installed too in order to make the child theme works.