To help things, i will meet you at the Thalwil train station and guide you to the club. after you arrive at thalwil you will need to quickly walk up the stairs - make sure you take the stairs furthest down the platform - in the direction the train is going.
normally, the journey from zurich HB is only 19 minutes to the tennis/bad club. since its the first time, i would suggest taking the following train. i will meet anyone who is coming on this train
Zürich HB27.11.08 dep18:3853
S2 18277 Urban railway, line 2,
Thalwilarr18:513CD
Thalwil
Alex