How to get custom page template content showing in text or visual editor in Wordpress?

Apologies if this is a silly question, I have build out a wordpress theme from scratch but when checking the visual or text editor from the dashboard there is no content showing, which of course would be very useful, firstly for content to be updated directly from the dashboard, as well as for SEO content (Yoast claiming there is no content on the page). In my search for a solution one possibility was to declare at the top of the page php file, for example on my page-contact.php file:
<?php /* Template Name: page-contact */ ?> and then in the dashboard under page attributes to set the corresponding template (i.e. page-contact). No luck with this unfortunately. Then it seems that I need a loop on the page, but checking a page where I do have a loop there is still nothing in the editor. Be great if someone could help! Working through the Treehouse tuts I don't remember this being covered, although could be wrong! Regards, Nic