Hi Steph, welcome to the group! (You should check out the V Section - it's where the cool kids hang )
In regards to your loan, as Chef said, a secured loan essentially means that you are offering the bank some form of security regarding the payment. 9/10 times this is the vehicle that you're purchasing. For a vehicle to meet their criteria, it must be registered in Australia and in a road worthy condition. You provide the bank with all the details, ie VIN, Chassis No, Engine No, Plates, etc. and they go and ensure it's a legit purchase. They also make sure that it's a reasonable price. They don't want to give you $30k for something that maybe only worth $20k.
Best bet is an unsecured loan which does have more stringent borrowing criteria and higher interest rates. Alternative is, buy one that has already been registered here.
Hope that helps.