Pumps have a charcteristic that they will produce a certain flowrate at a certain head. I assume you mean 396 gal/hr at zero head. As the head is increased by adding more pipe to the pump exit, the flowrate decreases, up to a point where there will be a maximum pressure at the pump but no flow. By plotting several points on a graph of flow versus head, one obtains a pump characteristic curve.
The system curveon the other hand of all the losses in the pipe is more difficult to obtain as Russ mentioned.
The intersection of the system curve with the pump characteristic curve will give you the point at which the pump is operating.
The 6 foot pipe section upwards will give only the elevation head loss for the system curve.