There are a number of great resources which can help you/your students prepare for the OzGrav Australian Space and Astronomy Olympiad.
Check out Mission Gravity to learn about the star cycle and different types of stars using an interactive simulation:
https://outreach.ozgrav.org/portal2/resources/mission-gravity-teaching-resource
If it doesn't work try using a different browser.
Stellarium is an open source, free planetarium for your computer. It can be downloaded as a software that runs on your computer: https://stellarium.org/
Alternatively, you can use the web version with no installation required: https://stellarium-web.org/
You can use Stellarium to learn to identify stars and different constellations and become familiar with celestial coordinates. It shows a realistic star map, just like what you would see with the naked eye, binoculars or a telescope.
We have a number of training booketls which contain notes and practice problems which you can use to introduce yourself to more advanced concepts.
A great way to get familiar with using telescopes and the night sky is to join a local astronomy club. Here are links to some of the astronomy clubs in Australia by state:
ACT - Canberra Astronomical Society
NSW - The Astronomical Society of NSW
Queensland - Astronomical Society of Queensland
South Australia - Astronomical Society of South Australia
Tasmania - Astronomical Society of Tasmania
Victoria- Astronomical Society of Victoria
Western Australia - The Astronomical Society of Western Australia, Stargazers Club WA