Hey Giulia,
What you’re trying to add is called Open Graph and our themes does have a basic Open Graph integration. You can read about that at https://theme.co/apex/forum/t/customizer-social-options/141
If you wish to use your own Open Graph, you need to make sure that you disable X Open Graph in X > Theme Options > Social to avoid Open Graph setup conflicts. Then, install and activate the X child theme. You can read more about that procedure at https://theme.co/apex/forum/t/setup-how-to-setup-child-themes/57
Once the child theme’s setup, add the code below to functions.php. My suggestion assumes that you understand a bit of PHP. If not, skip the coding and use a plugin. You can read more about that in this third-party article: https://kinsta.com/knowledgebase/add-code-wordpress-header-footer/.
/* Describe what the code snippet does so you can remember later on */
add_action('wp_head', 'your_function_name');
function your_function_name(){
?>
PASTE HEADER CODE HERE
<?php
};
Please note that the use of custom codes and third-party plugins are outside the scope of our product support. In case you encounter issues with them, please get in touch with the plugin developer or a web developer.
Hope that helps.