with convert and FormalPowerSeries one can find power series of some functions. WIth the function int one can sum / make integrals of expressions.

I am new to Maple and have tried finding the sum function of the product of two power series :

in both cases sum of n from 0 to infinity
 
how to program Maple to find the sum function of f(x), g(x)
and g(x)*(f(x) ?