Here I will just give you some ordered pairs
F(1) = 3 - 2 = 1
F(1) = 1 and in ordered pair terms (1,1)
F(2) = 3-4
F(2) = -1 and in ordered pairs terms (2,-1)
F(3) = 3-6
F(3) = -3 and in ordered pairs terms (3, -3).
If you need more tell me but basically plug in numbers in f(number here) and then plug that number into your function.
Hope this helps.