Explanation:
The 2 in 2x is the slope. You can also think of it as 2/1. The -3 is the y-intercept. This is the number that the graphed line touches on the y-intercept.
So, you could start at (0,-3), then use the slope to plot the next point. Graph the next point by going up two boxes from (0,-3), and then going one box to the right. It should look like this: