Hi, Angela,
 
don't despair!
As Canto 81 is one the most widely dealt with Cantos there are MOUNTAINS of literature about
it.
I'd suggest you get from yr library & try
 
Anthony Woodward:
Ezra Pound an the Pisan Cantos
Routedge & Kegan Paul
London/Boston 1980
 
esp. the introduction and then pages 82 ff.
 
Cheers,
 
alex