Page names: As a page name you can choose something similar to 'My Pagename'. However, the system will create a link for the page and the menu like this: 'my_pagename'.

Create new page: Right click on the menu item on the left under which you want to create the new page and choose 'New page here'

Edit a page: Right click on the menu item on the left and choose 'Edit' or click on the settings-icon on top right and choose 'Edit this page' to edit the current page.