Here is a link to the process of bringing you fiance from another country to the US for the purpose of getting married.

http://www.uscis.gov/portal/site/usc...0045f3d6a1RCRD


The process is very complicated, you have to make sure you fill out the paperwork properly and send it to the correct places. It is highly recomended that you hire a lawyer to help.

To Summarize

You must file a form with the US government, Form I-129F petition for Alien Fiance. The approval time for this petition is usually taking about 6 months.

Once this is approved, your fiance will have to visit the US consulate in Australia and get a VISA so she will be allowed to come to the US for the purpose of marriage.

Next, your fiance should come to the US.

You must then get married within 90 days of her arrival in the US, or she will have been considered to have overstayed her VISA and can be deported.

Once she is here, and you have married, then you need to follow the procedure to adjust her status to a US permanant resident so she can stay in the US after the marriage

Below is a link to that process.

http://www.uscis.gov/portal/site/usc...0045f3d6a1RCRD