As a Working Holiday Jobs Member you will be entitled to a discounted Tax File Number setup service from Taxback.com. Sit back and relax while they sort out your TFN. This service normally costs $30 but you’ll only pay $20. If you complete your Tax Refund with Taxback.com, they’ll add $20 to your refund! Premium Members get this service for free, upgrade to premium for only $5 per month.
 

You can also get an unassisted tax file number setup via the Australian Taxation Office.