I'm not sure which bit you're struggling with, but:
Remember n is the number of intervals (not function values)
h = (b-a)/n = 8/4 = 2 (where b=9, a=1, n=4)
so now since we need 5 function with each producing a shape of height 2: sub these x-values into the function: 1, 3, 5, 7, 9
5...