There are 10 IDPA clubs in California. The website for IDPA is . Check it out. Contact a club near you and go to one of their matches. Explain that you are new (everyone was once) and I'll bet they knock themselves out helping you become a regular.
Every USPSA or IDPA club I've ever shot at was helpful. 99% of the shooters will treat you right. I hate to admit it but sometimes there will be a snob looking down their nose at lesser experienced shooters, but they are really few and far between.
Get going and have a bal!