A room? Well, to get a room in the Stock Pot Inn, you have to get to the Hotel before 2:00 in the daytime on the first day (before the Mailman arrives at the Inn).
You talk to Anju then and she'll ask you if your name is (insert whatever name you called yourself in the game). Reply yes and she'll then proceed to give you the key to the room.
Also take note that you must get there and do this before a goron arrives at the Inn. If you do this after he has gotten there, it'll be too late to get the room. He should arrive shortly after the Mailman comes by.