First you need to figure out how to get out of the room. Somewhere there should be a key. Carefully look around, search the furniture and study the contents of the drawers. Youll have to do this quite often, so start getting used to it right now. There are quite a number of such rooms in the house, and in each there is something necessary to escape. Only by collecting all the needed items you can turn off the alarm and unlock the front door.