Of course!
Each room and apartment has bulletin boards you can use to hang up posters, pictures, etc. No items may be attached to the wall with tape or nails but you can use white UHU-Tac (which is provided by your head resident) for putting things on the walls.
You can use 3M Command hooks and picture frame hangers (or equivalent product) at Wal-Mart or K-Mart for easy hanging of pictures and other items. Please do not hang items on ceilings or windows.