You can't transfer existing Qantas points into American airlines points. You'll need to actually earn the miles through AAdvantage.
There are a few ways to do that from within Australia, including:
-Diners Club points can be transferred to AAdvantage
-Amex Membership rewards points (through credit card spend) can be transferred to SPG then onto AAdvantage
-You can buy the miles for USD$29.50 per 1,000 (though there are often bonus deals which reduces this cost)
-Crediting flights (on any oneworld airline or other AA partner) to AAdvantage