It's similar to Canada. Look up your occupation. It is either in the skilled occupation list (SOL) or Consolidated skilled occupation list (CSOL). If your occupation is on the SOL, you can get PR. If it is on the CSOL, you need a state nomination. If you get a state nomination, you get a 4 year visa leading into PR. In that 4 year visa, if you need to work in that occupation for at least 12 months over a 2 year period, you can get PR and go anywhere you want. Until then you are bound to the state and cant go anywhere else.
You have to get your skilled assessed and then enter an EOI. They have draws and then send an invite. The good think about the Australian draw is that they announce the dates and the number of invitations in advance so you dont have to refresh the page like a Canadian draw.