Your first graph:
points:
(0,-1) (1,4) (2,9)
Should look something like the green line, you put a point at (0,-1) for your Y intercept, then you do your slope which is the 5 in 5x. 5 is the same thing as 5/1 so you rise 5 up and run 1 to the right which will bring you up to (1,4) then you rise and run again to get at point (2,9).
Second graph:
points:
(0,10) (1,15) (2,20)
Should look something like the blue line, you put a point at (0,10) for the y intercept, then you do your slope of 5, just like the last one. You would go up 5 and over 1 (rise over run) to get (1,15) and again to get (2,20)