Studentenwerk (student services) is an independent organization that is responsible for student housing in Dessau.
For Dessau you can also check in Bauhaus guest house as many students live there as well. There is an special option for students. (You can live there temporarily for a few days as well.)
Also for short time you can stay in the youth hostel in Dessau.
There are a lot of ways to find private housing in Germany. However, you should bear in mind that shortly before the semester starts, it will be more difficult to find a room. So take a look in advance. Usualy the rooms and apartments are offered unfurnished. Most of these apartments even do not have kitchen.
Useful websites for private housing:
You also can check out the "Dessau International" Facebook Group. People are always looking for a new room mate.
If you have any questions, please contact Mrs. Yili Lu via E-mail: yili.lu(at)hs-anhalt.de .