Zurich airport (ZRH) is the main one in Switzerland, and has plenty of international flights. It is very well connected to the city center with public transportation.
From the airport, there are 2 options to reach city center:
You can find your itinerary on the swiss national ralway website or on google maps.
There are many trains to Zurich from all over Europe. Direct trains can be found from Paris, Milan, Hamburg, Berlin, Munich, Vienna, Budapest, Zagreb, ... Please visit this page for details.
The conference place is at a 15-minute (uphill) walk distance form Zurich central station (Zurich HB).
Trust us, driving in Zurich is not the best experience of your life. If you do need information about driving to/in Zurich or parking, please contact the organizers.