Firstly, if you are new to Flinders, you'll need to get your username and password from a teacher, most likely your homegroup teacher. You will keep your username throughout your time at Flinders, but should change your password frequently. When you have obtained your password, you can then Connect your own device to the Flinders Network. and learn how to Print from a BYOD device. You can also install Office 365 on your device.
Secondly, you'll want to learn about using Moodle, messaging your teachers using Moodle, and possibly logging into your Google Apps account.
If you have difficulty with any of these things, your first port of call is your teacher. If you need further assistance, your local IT technicians will be able to help you out.