When x = -6, y = -(2/3)(-6) + 1 = 5
When x = -3, y = -(2/3)(-3) + 1 = 3
When x = 3, y = -(2/3)(3) + 1 = -1
Thus, we have the points (-6, 5), (-3, 3) and (3, -1).
Plot them on a graph, draw a straight line through all three of them, and you will have your sketch.