Pilot:
You have asked a very broad question that is difficult to answer properly in a forum like this.
Some specific information about the Swordfish aircraft and its role in operations against the U boats is available at the excellent uboat.net site:
http://www.uboat.net/allies/aircraft/swordfish.htm
The above page includes references for further reading and also includes links to pages that discuss the ASV radars fitted to Swordfish aircraft.
I'd suggest the above as a starting point on what is a big topic.
Cheers
Boomerang