After adding a new page to your site in WordPress, it’s easy to add it to the navigation menu.

1. simply visit the Appearance -> Menus panel in your site admin
2. Click Menus, and then click Primary.
3. Click Add Items.
4. Click the + icon next to the page you want to add, and then drag it to the appropriate location.You can add it as a sub menu item by dragging it to adjust its position.
5. Click Save & Publish.