You can request a patent for your invention using online services.
If you have a provisional application, you will need to apply for your standard patent with 12 months in order to keep its priority date. If you have a patent application overseas (a convention application) and want similar protection in Australia, you will need to file your patent application within 12 months of filing your overseas application.
You application form needs to be accompanied by a patent specification.
The complete application is then published in the Australian Official Journal of Patents 18 months from the Earliest Priority Date, being the date your application was first filed.
See the standard patent application fee.