Transitting through Beijing and Shanghai, from Melbourne to Italy

Hi, in September I will be travelling from Melbourne, Australia to Italy with an overnight stop over in Beijing on the way there and a (day only) stopover in Shanghai on the return trip home.
Do I need to apply for a visa or am I elgible for the 72hour free transit?
If I am eligible for the 72 hr free transit, is there anything I have to do?