Beginner's problem

Hello all, 
At the moment i'm trying to use octopus to get the maximum volume of a tower lofted from a curve in rotation, my gene pool is the rotation value i'm not quiet sure if i set the rest of parameters in the right way, also, if i want to have the min. surface area what should i do? 
thanks in advance, please correct me if there's something i dont understand. 
Thanks again.