Hello, @denys-lvov,
1. You can edit the header by editing the elements used in it from here: https://plantaboost.com/wp-admin/post.php?post=6965&action=edit
2. To add the custom HTML code to the header, you can use the RAW HTML element in the header and set it as per your requirements: https://postimg.cc/CRLZD5gG
Best Regards,
PThemes Team.
