If you wish to be kept up to date on the VK APRS scene, join the OZAPRS Mailing List, which is used for announcements and discussion. It’s a great place to ask questions and learn more about APRS.
For general information on APRS, see www.aprs.org, in particular the APRS 1.0 Specification, or the 1.1 and 1.2 addendums.
For amateur radio in Australia, not specific to ARPS, see the Wireless Institute of Australia, or the ACMA.