Legalities of adopting overseas children and bringing them into Australia. Any help will do!?

I am thinking about adopting my cousins so that i may bring them to Australia, this is all with the consent of my Aunt, however i am finding it difficult to find the information i need. If anyone can tell me where i can find some info or if they have done this and have any pointers on how to even start the paperwork i would be very greatful