That all depends on what faculty you are from.
The IT faculty have an online eVOP system, from which you can change subjects and tutorials starting from the week before Spring semester.
If your from the Business faculty, you can change anytime from now (I believe) up until 2 weeks into Spring semester. The Business faculty are very tight on changing tutorials and they will require you to have a letter from your employer or something similar to show you have a clash.
You can log into MyStudentAdmin
http://www.uts.edu.au/onestop/studentadmin/ to check what subjects your enrolled in, however they don't seem to show what classes you are enrolled in at the moment, which is a bit of a bummer. If you are not from the Business faculty, then perhaps your faculty office will print out an Enrolment Advice for you, which will detail what you are enrolled in. Otherwise go hunting for the Enrolment Advice you got when you enrolled.
The procedure for all faculties (except IT) is to go to the student admin centre for that faculty and fill out a VOP form and submit it there. If your adding/changing subjects outside of your home faculty, then you will need to get the VOP form signed by your home faculty.
