If you search the site, there are a TON of threads discussing backspin:

http://www.golf-tuition-online.com/v...ead.php?t=1577 (Backspin)
http://www.golf-tuition-online.com/v...ead.php?t=2797 (backspin)
are a few of the most recent threads.
Go to the search link on the top menu, type in 'backspin' in the keyword search - you will get a TON of results.