Dynamic Yoga is a generic term for any active yoga. It normally is based on Hatha Yoga poses with an emphasis on movement and breathing. The class will probably start with several rounds of Sun Salutations, followed by a variety of standing poses.
As the name suggests, dynamic yoga is movement based and will probably not involves as much deep stretches as a hatha class. It will increase the heart rate and probably make you sweat.
Often Dynamic classes are based on the standing series of Ashtanga, without the strict adherence to a specific sequence of Asanasa (poses) and Vinyasas (breath). There may be some time at the end for inversions and back bends, normally finishing with sivasana.
Bring a towel and make sure not to eat at least 3 hours before the class. Probably best to wear stretchy clothes as well.... Cairns has an amazing selection of dynamic Studios and Teachers to choose from.