I am not familiar with the tutorial you are refering, can you provide a link please.
to edit an html editor instance, you do not edit the page in the html edit folder, you edit the page it was applied to. In this case the admin/contents_results.php.
the code that ios displayed on the page in question is because the file has a php extension, it is showing the javascriot code ion the design view.
this is not a problem, this is the way this update page is supposed to be.