To configure your menu and your pages, first click on the Pages tab, then, in the orange panel with the list of your pages, you can modify the page order and hierarchy, by drag and dropping them with your mouse. By clicking on the current page title, you can change the name and SEO settings of the page.
When you select a Menu block on your page, the Manage pages button in the blue panel allows you to choose the pages listed in the menu and the pages displaying the menu.