These are good sources for learning about upcoming tournaments, staying in touch with the current events in badminton, learning the rules, purchasing videos of recent tournaments, and getting tips on how to play:

Local Tournaments:
  The Charity Open in early April

  Howard County Open in late July (see MAC link above)

Beginners Guide to Badminton:
from Playground Equipment.com

The United States Badminton Association:
http://www.usabadminton.org/

The International Badminton Federation:
http://www.intbadfed.org/