Look at my top end take apart and rebuild for some info on putting the piston back into the cylinder and the way the rings fit on the piston around the ring pins etc. the wooden piston support stand will really make putting the piston in the cylinder very easy and you will not have to fight it as much. the wooden tool can be made out of a wood shingle or wood stirring stick even a couple of popsicle sticks will work in a pinch and you can run down to the min mart and get your favorite flavor eat it then use the sticks.
Norman
Look up 2 stroke engines on Google there is a lot of info on piston and cylinder clearances etc and why a 2 stroke will seize. these engines run with some very close clearances compared to 4 strokes. warming up a 2 stroke before putting it under a load will stop a lot of seizures.