The basic process is:
Note: For 99% of people, the process must be completed in the order given, that is practical pre-learner course, before sitting the Rider Knolwedge Test (RKT). The exception is for those who are converting an international licence to an Australian one.
You can find more detailed information directly on the RMS website - Getting a rider's licence
You can find the riding training centres that run the pre-learner course here.PRE-LEARNER course providers