In Germany, on-campus accommodation offered by the university itself is not a very common thing. Therefore, students should independently start looking for an apartment.
You can either apply for a room in a dormitory via the Studierendenwerk (places are limited!) or find a flat on the privat rental market.
Since flat sharing (everybody has his/her own room while sharing common rooms like bathroom and kitchen with the others) is a very common concept among students in Germany, you might find the following link quite helpful.
Apart from that, you can find information concerning apartments in the daily newspapers, the university bulletin board, or the respective study program coordinator.