To define the Target curve for a given entity, use the controls in the lower-right-hand box. More information on how to do this is found in the Changing a Curve section. (Hyperlink)
To change the Total curve for a given entity, change the subcurves by either a) double-clicking on that subcurve and defining a target for the subcurve, or b) clicking on the “Synchronize subcurves with target curve” box. This function automatically gives the subcurves the same shape as the target curve and sets the total of the subcurves equal to the target.