Like others have said the IP Australia site and find a Patent Attorney. At this stage don't worry about things like manufacture, distribution, etc the thing is to tie up the design/idea then worry about stuff like that. Keep the discussions with others to the very minimum until you get paperwork processing.

I used to work in R&D as a Chemist for a large multi-national and we would patent - or at least try to - everything we could so that opposition companies would be limited in copying or competing with us. Keep notes, etc of what you have, especially with dates, etc for the idea/design you have, things like that become important to show you had the idea/design first if someone tries to appeal/block your patent application.

Best of luck with it.