The university enrolment fee covers your semester ticket, which allows you to use public transportation in Berlin. The ticket applies to S-Bahn, U-Bahn, Bus, Tram and even some regional train and Ferry trips. Timetables and routes can be found on the BVG Website: www.bvg.de.
Exploring Berlin by bicycle is a great alternative to public transportation and an excellent way to get to know the city. As the university is quite spread out, you may wish to get a bicycle to cover the distances between the administration offices, the cafeteria, the GEAS and various libraries on campus.