To create a minature flow chart of your site, click on the New Page button, and a Home Page will appear.

You can add more pages to your site simply by clicking on New Page again and again.

Alternatively, you could right-click on any of your thumbnail pages, and choose 'New Page" from the menu that appears (see the illustration on the right). 

OR

A final way of adding pages to your site in Navigation view, is to right-click while holding your mouse over the 'Folders' panel (see below).

If you choose this last option, no thumbnail will appear on your site tree.  Instead, a new file will appear in your list of files and folders. You can name the file, and if you want it to appear on your site tree, just drag it there! You will see, as you drag the file,  a dotted line showing you where the new page will be added.