Sketch a line passing through the point and having slope m. (0,6), m=-3

now, to graph a LINE, all you need is two points, so, you already have one, 0,6.

to get a second point, simply apply the rise and run values, so 0+1 = 1 and 6 -3 = 3, thus there's your second point, (1, 3), graph it away.