if i have a pic like this
how would i get it to stay over a head that is moving all the time like this guy
did with the moasic
You need to track the motion. If the eyes are visible all the time, use them as the tracking centers. Apply the tracked frames to the covering image, then adjust the anchor point so it appears centered over the face. For more elaborate stuff you may need some expressions, but that entirely depends on the type of footage.