Many agility trials are not advertised other than through agility mailing lists, schools and the sanctioning organization. Here's some websites you should explore (many have listings or search engines that you can use to find agility trials):
htt://www.agilityaction.com (this is an agility magazine)
http://www.cleanrun.com (also an agility magazine)
Here's a link to more info (read the last post - it lists sources of other info on dog agility) The cross post is an article I wrote for The Yorkshire Terrier Magazine:
http://www.webpagetutor.com/mightymi...?t=13&start=15