These are some useful links to websites for rocketry.
Tripoli Montana - https://www.tripolimontana.org
Tripoli Rocketry Association - https://www.tripoli.org
National Association of Rocketry - https://www.nar.org
Lethbridge Rocketry - https://www.lethbridgerocketry.com
Utah Rocketry - https://www.uroc.org
Lift Off - https://www.elevators.com/lift-off-model-rocket-maintenance-and-technology/
(The last site in the list above was suggested by a young man who found that it provided value for him. Thanks, Lucas!