Please tell me how to find my family

Don't know for sure, but some possible suggestions off the top of my head :

-Advertise on the net (in large Australian forums or some such)
-perhaps advertise in a paper if believe they are in a particular area
-Start where you last knew they were
-White pages online
-google search their name
-check myspace, and facebook
-hire a Private Investigator
-Electoral Commission (not sure exactly how good this is)
-Valuer Generals (or State equivalent) searches
-Land Titles searches
-Rates searches
-Births Deaths & Marriages Registry (if you think they've changed their names)
-not sure if you can search driver licences

If you are of particular heritage (Greek, Italian) you can try various Greek/Italian clubs around the country.

It may be that you will have to search in the country of your fathers birth, for more details about his brothers.