Munich airport is well serviced by major international carriers. The easiest way to get to town from the airport is on the S1 or S8 trains. The trip on the train from the airport to Hauptbahnhof, Munich’s main station, takes about 40 minutes.
If you stay central you can cover Munich’s attractions on foot. If you do need public transport the S-Bahn and U-Bahn trains are extremely efficient and easy to use.
If you want to get a good overview of the city go on a bike tour with Mike’s Bike Tours which cost €24 for a half-day.