Without calculator: make a set of data points by inputting values (-2, -1, 0, 1, 2) for x to figure out the corresponding value for y. After you plot the points. For an example: y=5x so the data set would be: (-2, -10) (-1, 5) (0,0), (1, 5), (2, 10). You take these values and plot the numbers on a graph.
With calculator: enter the equations in the y=. The first equation in y1, second in y2, and third in y3. Hit the graph key to see all three. If you want to see the data points hit the 2nd key, then hit the graph button.