It depends on where you live, but local gun ranges will usually have info on it. Many ranges will host their own training. This training may be more novice in quality, so if you're more of an advanced shooter with more experience on the gun, you may have to look to better training.
There are also regional or state gun forums abound to find that stuff.
Also, you can check out the NRA's website and locate training near you.
I have no need to take most of the training offered locally because no one around teaches the real advanced skills that I need. The basic stuff is overly repetitive for me. So, I watch training companies and groups that hold courses nationwide. EAG Tactical, Vickers Tactical, Viking Tactics, Trident Concepts, Magpul Dynamics, RedBack One, etc. For those, it's a matter of looking online and watching. Often times, you may need to travel to get to those courses. Otherwise, going to an established academy is a great thing to do. Gunsite, Thunder Ranch, US Training Center, Rifles Only, and others are great established academies. It all depends on your focus for training, be it skill-based or tactic-based.