OK - I literally just tinkered, and then stopped when things did not work out. All I did was install nginx, then installed the php-fastcgi. I didn't do any configuring afterwards, since I assumed (naively) that the two would work together. nginx was working as I got the test page when surfing to 'localhost' on micorb. After installing my php app, I got the app's diagnostic telling me that gzip wasn't enabled, so the install could not proceed further.