In MYSIT you can find the IT Help tab. It contains a list of frequently asked questions about the IT services available to you and where you can find further assistance if required.
Browse through the topics here and refer to this page if you are unsure. You may find the answer to your problem without needing to call the Helpdesk.
When you do have technical issues you can log a job with the Helpdesk using the online form on this page or alternatively contact them via phone or email. Please ensure that you give them your student ID number, your name and a good description of your problem.