Getting to Munich:

The main airport in Munich is called Franz Josef Strauss and has the airport code MUC. It is located roughly 20 miles (35 km) northeast of the city. Flying into this airport is the easiest option not least because of its accessibility to the city. From the airport, you can take a taxi for about E50-60 or the suburban train for no more than about E10 per person. If you're flying with someone else, group tickets are worth considering.
There are two train lines that will take you directly to the middle of Munich: the S1 and S8. Both of these take about 40 minutes to get to the central train station and the very middle of the city. Here is the link to download the transportation network: Netz (the airport is at the very top right corner).
Whether you will stay the night in Munich first or go directly to the wedding, if you're not driving, you will need to catch a train from the central train station.

Getting around:

The public transportation in Munich is decent, but once downtown, it's a nice city to walk around in. Here is the English link to the transportation website: MVV.