You are in the proper place to generate the NFO. It's just not being generated properly.
When you have a proper NFO file, if you double click it, it will reopen the System Information app to show you what's in the file.
So save the NFO file again, then close the System Information app, then double left click the NFO file, and it will either open the System Information app, or it will say this:

- corrupt_nfo.png (4.97 KiB) Viewed 1767 times
If it says that, save another NFO file, until you get one that works.