Also, the notch that is in the groove, both ends of the piston ring butt up againest it. I put them on this way. Use some type of oil. I start with one end of the ring and work it around the top of the piston until it is all the way on it, maybe a 16th of an inch or so, then slide it down until it is seated into the ring groove on the piston.
then slide the cylinder onto the piston till it meets the ring. Lay the cylinder on a table so the connecting rod is up. Push the piston ring in so that it is compressed into the groove on the piston, then carefully slide the piston into the cylinder.