Thanks! I uploaded the html file, left it where moodle put it (didn't move it into a folder), and just put the simple file name in the "File Name" field and it worked great. Now it works.
1. I'm confused about the "Hotpot" and the "New Hot Potatoes Module" you refer to. (So I'm also confused about which one I have installed.)
2. If I want to move the file rauding-jmatch-v01.htm to a folder (e.g. /hotpot/rauding-jmatch-v01.htm) how do I specify that in the "File Name" field.