Once your gym is up and running, it's good to get a rhythm going by having a consistent schedule of classes/activities.
ClubRight makes it exceptionally easy to setup these kinds of reocurring activity.
The above section of the diary entry creation dialogue is what's important to repeating events. The "How often?" box decided on what basis the evnt will repeat with daily, weekly, monthly, and yearly as options. Further customization is available with the box next to it, so you could do an activity every 2 months, or every 4 weeks, and so on.
Beyond this, you can also manage which days the class will repeat on, if you wanted a twice a week class, and for limited run events you can end the repeatition after a set number of occurences or on a specific date.