Submenus are a great way to organise a large website. Add multiple subpages do your submenu page, move content in or out of the submenu as your site changes, and have the subpages accessible via popout or dropdown menu.
To allow subpages to be added to an existing page on your website, there are two different methods. How these submenus appear on your website will be dependent on the theme you have chosen for your website.
Things to watch out for