Thanks for the help. I had been going to localhost and then phpMyAdmin to get to the database where I saw the category related tables. Once I logged into the web site itself as the admin instead of my own user ID (I have been testing as a regular user), I found the admin tab you mentioned.
Now I feel a bit silly since I see all the work I was doing to configure via direct modifications of the tables (after searching the code, a.k.a. "developer documentation", to see what code used what data) is doable via the admin tab.