If you are planning to go to university straight away after obtaining your HSC, most of application process is done for you through the UAC (University Admissions Centre) when you pay a fee of $26. About half way through completing Year 12, you will receive a letter with a special login and password you will use to lodge your course preferences through the UAC website. Your ATAR will be sent to the UAC after you complete your exams and you will soon find out whether you were successful in your enrolment of your first preference. There are various cut-off dates to change your preferences and a variety of university round offers to give you a chance to enrol in your other nominated courses even if your ATAR didn’t meet the cut-off for your first course on the list.
These stages of selection incur late fees if you don’t meet the deadline, so make several notes on your calendar. For more info, check out http://www.uac.edu.au/undergraduate/key-dates.shtml
http://www.uac.edu.au/
http://www.uac.edu.au/undergraduate/apply/application/
UWS-specific information at http://future.uws.edu.au/applynow/hsc_ug