There is mainly federal legislation covering the establishment of a company and then some registration within a state.
Best thing is to probably have a chat with an accountant who will be familiar with the process and you'll probably want one for doing annual returns for Taxation and ASIC (Oz securities and investment commission).

One question that should be asked and if the accountant does not raise it, then maybe you need a better one - is the keeping of personal and business interests separate, for if a business goes belly up with debt, it would be good to be able to declare bankruptcy without any personal assets being lost.

Should add too, that you could do some preliminary DIY research by seeing if the state you're in has in government departments a small business or development department (In Qld. it is actually called Small Businesses One Stop Shop or whatever and was under Consumer Affairs when I referenced them once) and you should be able to get a swag of free info for reading up on - it may just relate to state requirements/support, but a start.
Also go to the ASIC website and even ATO site too as it has a lot of general info.