How to bring someone from overseas ?

I am in a long-term relationship it's been 10 years now. However in last 2 years she's in my country and I've been studying in Australia. I feel that is about time to get marry and take that step. Now my problem is that everyone tell's me different someone said that I will have to go back and get married in my country and others said that I can just do declaration form and bring her like that. It would be nice if I do not have to go back and cut those expenses. Is there anyone to give me exact information What is the best and quickest way to bring her here. By the way i have visa subclass 572.