Buses to the city center depart regularly from the Capodichino Airport of Naples (which is located very close to the city center itself). We suggest you to get off at the main train station, Napoli Centrale.
Once there, or if you come by train, you can take either a bus or one of the metro lines to reach your destination. On this site you will find a guide to all the kinds of public transport in-town, as well as other useful things to know about the town itself.
However, the Department of Humanities is 20-minutes far by walk from the main train station.