I was looking for a wrapper for an HTML file, like Joomla offers.
I found a way to load an existing HTML file into my Drupal 7 site using a module called insertFrame.
In /admin/config/content/formats/full_html select the box Include iFrame with auto-height feature.
to a page or post.
I still have a weird error message to fix:
Notice: Undefined offset: 1 in _insertFrame_getHTML() (line 118 of /myurl.com/sites/all/modules/insertFrame/insertFrame.module