Coordinates are read as (x, y) pairs. It looks to me like the first corner from the origin is 3 units right and 1 unit down or (3, -1). The adjacent corner looks like (6, -1). Maybe the next one down is (6, -2). The lower vertex looks to be (4.5, -4), but I can't be sure.
Read the x-coordinate first, then the y-coordinate. You don't have any interval markings on the axes, so it's difficult to give you accurate coordinates.