The Australian Tourist Visa allows you to visit Australia for a holiday but does not allow you to work. If you wish to work in Australia you will have to apply for a Working Holiday Visa.
For stays of up to three months (ETA Tourist Visa) you can apply for an ETA visa either through your travel agent or online at www.eta.immi.gov.au. Rather than using a stamp in your passport your details are stored against your passport number which are accessed when you enter the country. If you are from a country that is not covered by the ETA facility then you will have to apply by completing a form through your Local Immigration Office.You can also do this to apply for a Long Term Tourist Visa which allows you to stay for up to a year.