The main airport for Athens is Athens International Airport (Elephtherios Venizelos).
Once you get to the airport you should use the suburban train (not the metro!) See also: http://www.athensguide.com/airport.html
Trains depart every 2 hours and the journey time is 1 hour and 20 minutes. Note that you will have to change trains at SKA.
When you arrive at Corinth train station you can take a taxi to the campus (or the hotel) - it's not far.
