If you seriously want to box you need acess to a ring, sparring partners and above all things a real trainer:

http://www.boxinggyms.com

http://www.boxinggyms.com/addressbook.htm

http://www.boxinggyms.com/findgoodgym.htm

Alternatively I recommend asking around in local gyms and sports shops, they often get given numbers from clubs just incase some one like you asks for a gym :P