When you start to add a larger number of pages to your site you can make your navigation simpler by adding pages as drop down lists within a menu item. This can be done by adding pages with a parent page.
Add a parent page to existing pages
When adding a new page to your site you can use the options on the right hand side to assign a parent page, this will make it appear as a drop-down option within the navigation. From within the page editor use the ‘Page attributes’ option on the right hand side to select the page you would like the new page to drop down from. Once you have added a parent page make sure to publish the new page.
For example, if you added a my CV page to your site you might want it to dropdown from your About Me page/section of your site.