First go to the page builder and add a new page; /administration/pageBuilder.php. Add a column and drag up an HTML block and enter the text for your Refund Policy page. If you need more specific help on creating a new page then ask where you are having trouble. Once you have the page created then preview the page and grab the URL from the browser address bar. You give a name for the page and a URL for the page when you create a new page but grabbing the URL from the browser address bar makes sure you get the correct address.
Now that you have the page built, you can add a link to it in the bottom menu. Go to builders, bottom menu; /administration/bottom_menu_compose.php. Drag the New Item to the menu and place it where you wish for it to appear in the menu. Click on it and fill out the entries. Use an existing menu item to see how to fill out the entries. That is it, you have a new menu item and when you click on it it will take you to the Refund Policy page.