The advise in this forum post:
also applies here. A part that has the same pins will do to represent a part not present. For power there are two choices: the best one is to add a power source (a battery and regulator, a regulator with an external supply, although I don’t think there are external supply parts around) or just scroll down the core parts bin to schematic view and drag the V++ icon in to the drawing. The disadvantage to this is that it only provides a schematic symbol for power, it doesn’t actually provide power to the circuit (you have to remember to do that in some way for it to work).
Peter