There are two ways of knowing the direction of your apartment. First is you can use a compass, the device for finding direction which has a freely moving needle which always points to the magnetic North. Second you can fold a paper in such a way that four lines are made dividing the paper at 90 degrees. Place a compass on the paper in the middle of your apartment and allow to align the North and South direction with two of the lines on the paper. Extend these lines on the plot and mark it to have exact direction.