Rogaining and Orienteering are centered around competitions. Local Rogaines are regularly organised by the ACT Rogaining Association and the NSW Rogaining Association. Their websites provide a lot of information about the sport and events. Competitions are usually also listed on the trip calendar.
If you want to participate in a rogaine, you can sign up to a rogaining trip to sort out transport, to find team mates, and to let the club know you're going. However, you have to contact the organisers of the event directly (usually through their website) to register your team. Check the trip description for details, or contact the rogaining officer for assistance.

The club provides subsidies for rogaine competition fees. Check the competition funding page for details.