From the main station you can take any S-Bahn train on the main line towards Ostbahnhof, just one stop to the Karlsplatz-Stachus stop. Leave the station via exit G, direction Bayerstraße.

Or you can walk for 6 minutes.

The stop “Karlsplatz-Stachus” is located in zone M.

Information on local public transport in Munich (MVV) is available at:
MVV JOURNEY PLANNER