Australia has 2 CB bands; one has 40 channels around 27 mhz (sometimes known as HF 'high frequency' CB) and the other has 40 channels around 477 mhz (known as UHF 'Ultra High Frequency' CB). This info is for UHF CB;
Channel 11 (by law) is the call channel;
move to another channel for conversation after making contact
Channel 5 (by law) is the emergency channel
1-8 & 31-38 are for Repeaters (duplex)
Avoid using unless you choose to use a repeater
Channels 22 & 23 are for telemetry(data) only, no voice allowed (by law)
Channels 10, 15 & 16 are commonly used by 4WDers
Channel 18 is commonly used by Caravaners
Channel 40 is commonly used by Truckers