I want create a child theme for put some functions

Hello, I want set the child theme for do what the staff recommends here:https://hb-themes.com/forum/all/topic/suggestion-for-put-more-locations-in-map-settings/
But I don’t need change anything more or just upload the child theme into wp-content/themes and put inside wp-content/themes/HighendWP-child/admin/theme-options.php and in header.php all the changes which appears in the other post?

Thanks, I hope can help me with that.