A U.S. Lawful Permanent Resident (LPR) or Conditional Resident (CR) who has remained outside the United States for longer than one year, or beyond the validity period of a Re-entry Permit, will require a new immigrant visa to enter the United States and resume permanent residence. You can learn more about Returning Resident Visas on usvisas.state.gov.
If you are married to a U.S. citizen who is currently residing in Australia, you may want to consider having your U.S. citizen spouse file an I-130 petition on your behalf instead.
Once you have reviewed the requirements of the Returning Resident Visa and believe that you may qualify, you must prepare your documentation (PDF 276KB) for the interview and then email the Consulate to request an appointment. Once your request is received by that office, an appointment will be scheduled and a confirmation email letter will be sent.