Y = 2x
M(slope) = 2 or 2 (rise)
y-intercept = 0
From the origin (0,0) go two units up, then turn 1 unit to the right, the plot that point at (1,2). Repeat from Point (1,2), for two units up the turn 1 unit to the right at (2,4).
Your graph should look like the attached :-)