Using Calibre's manual
it was easy to create many new empty libraries. I opened a command prompt (all programs - accessories - comand prompt) then I typed in the following:
Calibre --with-library C:\Calibre_Library_1
Calibre opened with a nice clean empty library. I quit Calibre via ctrl Q and repeated a few more times with different library names quitting calibre between each run.
Calibre --with-library C:\Calibre_Library_2
Calibre --with-library C:\Calibre_Library_3
Calibre --with-library C:\Calibre_Library_4
Now I had 4 new libraries and I started up Calibre fresh from my normal desktop icon.
Now (to test) I went to Calibre preferences - general
(at the top) and changed the location of ebooks
to C:\Calibre_Library_4 and clicked ok. The book window refreshed and I saw the one book I had already added to that library. My only problem is the tag browser didn't refresh so it still showed the stats from my first rather large library I opened.
I started a thread here
and hopefully my error or calibre's error will be corrected. It looks like setting up and using multiple libraries is relatively easy.