Please see the following links for help with Excessive and Unwanted Barking...

http://ahimsadogtraining.com/blog/stop-barking/

http://www.clickersolutions.com/articles/2002/doorbell.htm

http://www.clickersolutions.com/articles/2001c/manicbarking.htm

http://www.dogstardaily.com/training/excessive-barking

http://www.sfspca.org/sites/default/files/dog-barking.pdf

http://www.clickertraining.com/node/237 & http://www.clickertraining.com/node/1125 (You need an account to see full training instructions in the www.clickertraining.com library. Signing up is free, only takes a a minute and will provide you access to tons of great training resource articles!)