Easy start is to attend one of the many “matches” or steel plate challenges near you. Like Federal Discount Gun indoor range has something every Tuesday and Wednesday.
http://federalwaydiscountguns.com/Also check out other indoor ranges for different days and also different platforms. Not just pistol, some have rifle and shotgun as well.
It is daunting to get involved and each have their own specific rules. Fundamentals are key. Some will require a holster and some won’t. You will just shoot from low Ready.
If you are truly interested in competing eventually.... check out the folks at Powerfactor Show. Their earlier podcast goes over all the equipment, safety rules etc.
https://m.facebook.com/powerfactorshow/If you want to see a match for IDPA/USPSA
Check out Renton Fish and Game Club.
http://www.rfgc.org and see their schedule. Cost nothing to watch. You may have to sign a waiver.
FYI - IDPA matches are typically on Saturday at RFGC
The basics - IDPA - you show up early, sign in, waiver, pay and do the safety brief prior to the match.
USPSA - you have to check with each club to find out who, what and where for new shooter safety check. You typically can’t do it day of a match.