Well, I'm going to assume you are in Washington, at least....
First check out www.idpa.com
You can do several things on their site -
1) is find locations around you
2) read the rule book - get a general idea of the rules and scoring
3) general hints on what to have and do for your "first match"
Another local site would be www.nwppa-idpa.com this is the Washington State Local Chapter of IDPA
There are many clubs in the area that host IDPA events each month and throughout the year in Washington State.
Most are held during the weekend. We all kinda work too. Well, I don't know if you want to call what I do work but they pay me really good.
Here are several locations but again since I don't know where you live...
*Renton Fish and Game Club every third Saturday
New shooters should arrive no later than 8am to go through their new shooter orientation
Marksman in Tacoma
Norpoint in Arlington
West Coast Armory in Factoria
Black Diamond Gun Club
North Whidbey Sportmen Association
Jefferson County Sportsmen Association
You can get the contacts for each when you check out the IDPA website.
When you read the "New Shooter" Basically you just need a good holster (one that will withstand multiple reholstering) and some magazines (recommend 3-5+). Ammo about 2 boxes+ The more is better for someone that is new but typically a match round count is anywhere from 70-120 rounds. Just depends on how many stages and how many shots per stage.
My biggest hint to a new shooter is go and shoot a match - make sure you check your attitude (this means several things). What I mean by this is one go with the idea you are going to learn something new. Take it slow and safe. Keep an open mind, the hints people give are meant to help not criticize. You are not going to be a "Master" level shooter on your first day. Be safe and make sure you follow the Safety Officer's commands. If you don't understand them - stop and ask. And lastly, Have fun!