Ok, I started pretty much from scratch. I changed from using my Windows 10 laptop to my Windows 7 desktop (everything is easier in Windows 7). I figured out last night that the version of iTunes was installed from the Microsoft store. If you click on the Help menu and you see "Check for updates", you have the Apple version of iTunes. If it doesn't have "Check for updates" it's the version from the Microsoft Store. This Windows 7 desktop didn't have iTunes installed at all, so I went directly to Apple, downloaded the version for Windows from there, and installed. Now I could see "Check for updates". Problem 1 solved.
Because I had wrestled with the mp3 to mpr filename change last night, I was able to follow the directions for Create a ringtone on the page linked above at https://discussions.apple.com/docs/DOC-12051.
The last step was to copy the mpr file from Windows Explorer to the Tones file on my iPhone. Drag & Drop didn't work, but Ctrl+c and Ctrl+v worked.
Then I had to figure out how to assign that new ringtone to a contact. That took me a bit because I didn't realize the Contacts app was not the same thing as the phone part. So it installed the Contacts app and I was able to assign a ringtone there, but using the "Edit" button...which doesn't make much sense to me because you can't see what ringtone is selected for that contact until you press the "Edit" button.
Anyway, several hours later (I'm not kidding, if I count last night) I finished and it worked. I think the webpage on the link could be tweaked a bit to make it more understanding for non-Mac users (maybe make it a completely different webpage?? It ain't like space on the 'net is expensive. LOL).
Thanks so much for your help. I haven't been able to figure this out for a while and I had given up. But now it works. :)
