First choose a few good x values. How about 0, 1, 2
y = 6x - 4
y = 6(0)-4 = -4 so we have the point (0,-4)
y = 6(1)-4 = 2 so we have the point (1,2)
y = 6(2)-4 = 8 so we have the point (2,8)
Plot these three points and draw a line passing through them. Remember that ANY point on the line gives you a pair (x,y) that satisfies the equation - so you're really visualizing an infinite set of solutions when you look at that line!