I went to Russia 2 years ago, but the visa application process should be the same. You will first need to get a letter of invitation to visit Russia. I understand that Top Deck should supply this so I would ask for it. You then need to go onto the embassy website and fill out the form
Once you have done that, my understanding is you print out the form, sign it and then send the form along with your passport, your invitation and the visa fee ($150 for an Australian citizen). If you live in Sydney you should be able to do this in person.
It takes a bit of effort but isn’t too difficult. Good luck!