From the Strasbourg airport: Follow the covered footbridge from the airport to the train station and descend to the track headed in the direction of Strasbourg. You can buy a ticket from the machines on the platform. There are usually about four trains per hour going to Strasbourg main station and the trip is only 9 minutes long. For more information, see the airport information website.
From the train station: Take bus no. 10 (1,60 €) until bus stop “Pont des Vosges.” Rue Gustave Klotz is a short street leading off the major Avenue d’Alsace, right next to an Agip gas station, and behind and across the street from the very large church St. Paul.