How do I create a very basic new non-shop page?

At the most basic...

1. Add a new folder to includes/modules/pages/ called the NAME_OF_YOUR_PAGE.

2. Add a new file called header_php.php, which needs to be something like...

<?php
require(DIR_WS_MODULES . 'require_languages.php');
$breadcrumb->add(NAVBAR_TITLE);
?>

3. Create the file includes/templates/YOUR_TEMPLATE/templates/tpl_NAME_OF_YOUR_PAGE_default.php

Add the html here you want to pull out.

The page will be at the url index.php?main_page=NAME_OF_YOUR_PAGE