Since you're in Billings, you might not find a paddle club. Billings isn't exactly the Montana mecca of boating
(Although some of the sickest runs around are hours from Billings, East Rosebud, Clark's Fork of the Yellowstone, sigh...) What do you want to practice in flatwater? As a new boater, I would recommend that you go out on the Yellowstone or Stillwater (which may be too low) and work on your eddy turns, ferrying and reading water. IMO these are so important to learn before you learn "tricks." Heck, eddy turns lead into stearn squirts, which lead into enders which leads into cartwheels... If you are at the point of learning "tricks," you could get a video (I'm sure lots of people on here probably have suggestions) or go down to Sunshine Sports and see if they know of anyone who might be happy to help you learn. Billings is a very small kayaking community. I'm sure the people at Sunshine would probably be happy to hook you up. Just a thought.
Good luck. Hope I see you out there.