Thanks for those helpful links, Applefreak!
I have been plugging away all night, but still can't get things working. According to the ][e card panel, my ProDOS partition is D2, S5. So I have tried typing many various versions of:
CAT, D2 ,S5
CAT, D2 ,S5, V0
CAT D2,S5
CATALOG, D2, S5
etc...