Take out the timing hole plug and line up the "T" mark on the flywheel with the notch in the side of the hole. That will put your piston on TDC. The timing plug hole is located on the right side of the engine, near the pull rope. It will be about the size of a quarter and I think it takes a 6mm allen wrench or allen socket to remove it.
For the cam, make sure the lobes on the cam are facing down and make sure the punch mark on the cam gear is lined up with the index mark on the crankcase. The index mark on the crankcase is right above the cam gear.