Weebly offers three possibilities to add codes into the header: Site header – code inserted here will impact throughout the site. Site level codes can be added under “Settings > SEO > Header Code”. Page header – code inserted here will impact the elements on that page. Page level codes can be added under “Pages > Select the page > Advanced > Header Code” Blog post header – code inserted here will impact all blog posts. Post level codes can be inserted under “Settings > Blog > Post header code”.