To use the Quick room wizard, go to menu Room | Wall, and press the button Quick room. Here you can choose a predefined room shape, saving you time from drawing the walls manually.
Define the length of each wall, click and type, use TAB to spring to the next field. Use the buttons to rotate or flip the room if desired. Press OK when finished. Note that afterwards the lengths of walls can be edited, but not the shape. Edit the wall properties in menu Room | Wall.