Congrats on wanting to start your own business.
Some basic steps to start with would be to write a business plan, decide how you will operate (web or physical site), decide your structure, decide on a name and check that it is available, register an ABN.
However, I can't stress enough, whatever your chosen field, first and foremost - make sure you do your Research! eg... Your product, your competitors, suppliers, marketing, Costs, anything to do with starting a business etc.
These sites will give you more thorough info on getting started, explanations and where to get more help:
www.fairtrading.nsw.gov.au/ (search google if you are in a different state)
HTH and good luck!