Landing pages display links to child articles. To include a new page you need to select the landing page to be a Parent.
1.
Edit a document
2.
Choose MENU SETTINGS in the panel on the right hand side
3.
Make sure the Provide a Menu Link is selected/checked
4.
Open the Parent Item Dropdown menu. Choose the parent Landing page where you would like the page to appear
5.
Parent landing pages are arranged alphabetically