Applying markup to travelify theme

I am looking for some guidance on how to add markup to my website which is running travelify. To this end, I found an effective guide described here: However, it seems that travelify is coded differently and cannot match the instructions on this guide. I cannot find the lines of code which I need to replace.
I would highly appreciate it if you could kindly help me with that.

There are no two exact themes available and you absolutely must know some basic PHP to make these changes.

Most of the structure related code can be find inside content-extensions.php file that you can find in Travelify folder - library - structure.

Make sure to backup your website before you attempt to make any changes.