First, install and activate MyListing child theme which is located in the downloaded package from themeforest.
Using a child theme is the recommended way if you plan to make code changes because this way, you will be able to update the main theme in the future and still keep your customization code.
Once you install child theme, you will need to edit functions.php file. There are 2 methods for this
Once you edit the file, you can add the snippet after the line //happy coding and save changes