Each dormitory typically has one network port per expected occupancy. That is, singles have a single network port, doubles have two, and pods have one per bedroom.
In most dorms, the network port is located right next to the telephone jack. They look similar, but a network cable is too large to fit into a standard phone jack.
If your connection has already been activated but you are unable to connect from your dorm room, you may wish to double check that you are plugged into the same port that was specified to you during the connection process.