By clicking the page+ icon above the page tree structure, a menu will expand below, with page type options. (Img. 2.1.1)
There are generally 4 types of pages available; "Standard" (a regular page that you can place content on), "Shortcut" (to link from the menu within the website), "Link to external URL" (to link from the menu to an external website) and "Folder" (a system folder used for special functionality, like news articles).
To add a new page, drag the page icon of choice down in the tree structure and drop it where you want it. You can either drop it between two existing pages, or you can drop it on an existing page, to make it a subpage. A title field is automatically opened and here you can insert the page title. Press "Enter" to save. To edit the title, simply double click the title in the page tree. (Img. 2.1.2)