Adding a new page is done outside of the page editor. To get to this page from the editor, simply click the 'Close' icon at the top right of the editor. Make sure to save any changes that you have made to your page before closing.
Here, you are able to add a new page by clicking 'Add Page at the bottom of the list of pages. You can also duplicate an existing page by clicking the 'Duplicate' icon on the page you would like to copy.
From this page index you can also edit your page settings (such as page name, description and page URL) or delete the page.