Follow the signs "Bahn/Railway" to the ticket counters or ticket machines. A ticket is valid for one hour for all trains to Zurich as well as for trams and buses in the city. If you plan to stay a full day, choose the day ticket, valid 24 hours, and take the escalator down to the train platforms. Trains to the city center leave approx. every 10 minutes. The ride to the main station (Zurich "Hauptbahnhof" or just "HB") takes about 10 minutes. Once you have reached the "Hauptbahnhof" change to tram #10 which takes you to "ETH/Universitätspital".
Alternatively a light rail connection "Glattalbahn" (physically the same as a tram, circulates as tram line #10) runs from the airport directly to "ETH/Universitätspital". Board on the platform outside the airport on departure level; trip time is about 30 minutes. Costs are the same as above.
We are in the building called CAB (map) at the "F" floor, one floor up from the ground floor "E" (building map for room F85.1).