That's a very big topic. What are you specific questions?
Join the National Pigeon Association.
Subscribe to Purebred Pigeon magazine
This show is next week. Smaller than many poultry shows, but worth the drive: http://www.sturbridgepigeonshow.com/
There are a few decent books, but not one real classic, all inclusive, up to date guide. I'll post titles later.
Get The Pigeon, by Wendell Levi. For years it was considered the bible, but now it is very outdated in some respects, but there is still a lot there that is relevant. Same with his Encyclopedia of Pigeon Breeds.