There should be a little pin in each ring groove. That is where the open end of the ring gets centered on, when the ring is compressed into the cylinder, it fits over the pin, ideally. You can force these pins in to far and ruin your piston. If not centered properly it will ruin the piston, ring and bore. If there is tiny marks by the open end gap of the ring, the markings go up. There should be an arrow on top of the piston, it points out the exhaust, or the cut out at the bottom of the piston goes towards the intake. Never reuse any gaskets, good insurance. Never take apart a bike without a manual, also good insurance!