In Content -> Pages click "Add Page" button and enter page name. The page name must be unique to your site. Then you will be redirected to the page that you just created. Check the video demo for how to use Page Editor to customize your page. The url to the page is <your site url>/Page/<Page Name>.aspx. 

There are two ways to enable page editor to edit page.

1) In Content -> Pages find the page that you wish to edit in the page list. Click "Edit" button to start editing.

2) Log in as admin and go to the page that you wish to edit. Click "Enable Page Editor" on the top left corner of the page.

In Content -> Pages find the page that you wish to delete in the page list. Click "Delete" button.