Click on Page tab, then click on the second Add button to add a new page. A pop up opens.
Type the name of new page and select the position where you want to add the page and press save.
New page will appear as the button of a menu.
In most cases websites have more than a single menu. Here you can choose which of the menus to edit or add. You can choose language of your pages.
You can also Edit and Delete the page if you want.