You can join and find out more info at geocaching.com. The website is where you join, get your GPS coordinates, clues, rate the geocache and log your results as a find or not found. And if this is something you are really into, there are higher levels of membership you can join. Some of these folks have large events that last a weekend and involve repelling, caves, etc.
I hope this is something your whole family can enjoy that will get you outdoors. If you decide to give it a try, our first one was titled: Mill Spring Park and Grab, a fairly easy one to get you started. And one of our favorites is in downtown Columbus. It’s titled Buffalo’s Polk County Settlers — you just might learn a bit on this one.