From Tullamarine Airport or Southern Cross Train Station transfers are available by taxi or Uber, which you can get from the taxi or Uber ranks.
From Southern Cross train station take tram no. 96 to Melbourne Museum and walk through the Carlton Gardens. Alternative catch a train from Southern Cross train station
to Flinders Street train station and catch any tram north along Swanston Street to University of Melbourne, then walk east along Grattan Street.
Another option from Tullamarine Airport is the Star Bus airport shuttle which will drop you off at the hotel for $22/person. The information on how to book is located at http://www.starbusshuttle.com.au