Content Sections
To add a link to an external site or a document on the website, go to Structure -> Menus -> Main navigation -> Add link.
Enter your Menu link title, which will appear in the menu. In the Link input box, add the full URL link of an external site that begins with https:// or a path to the file on the website, as shown in the screenshot below:
A page link can be added by entering the page name into the Link input box and selecting from the auto-populated values.
It is strongly advised to add page menus using the edit page interface.