To add HTML tags to the header/footer of a specific page, edit the page you wish to add an HTML tag to using Elementor. Click the page settings button in the bottom left corner, then click the Advanced tab.

Click the Custom HTML drop-down panel and you’ll see two windows.

Add HTML tags to your page’s header in the top window and add HTML tags to the bottom of the HTML body of your page, in the bottom window. 

To add HTML tags to the header/footer across your entire website, click the menu button in the top left corner of your builder, then click on Global Settings. 

Lastly, click the Advanced tab to add HTML tags to your website’s header in the top window and add HTML tags to the bottom of the HTML body of your site, in the bottom window.