what does "boring" the cylinder mean, and do i need to do that?

 

Boring is the same as drilling it out and making it bigger. This may be necessary if you have scored (scratched) the cylinder wall. If the scratch is too deep, then it has to be resleeved. This is where they make the cylinder a lot bigger then put a sleve in to bring it back to original size. If there is no damage to the cylinder you need to at least hone it when you put in a new piston. Honing roughens up the cylinder and allows the new rings and cylinder to break in together giving you a better seal. You shouldn't need a new cylinder unless the one you have is cracked or has some serious damage. But if you can get it running, even if it runs poorly, your cylinder should be ok. Pistons aren't very expensive. If you're going to change rings, change the piston as well.
If you don't have a lot of mechanic experience, you would probably be better off taking the motor out yourself and taking it in to a mechanic to do the work. I know from experience that if you don't have the proper tools you can bust the rings trying to get the piston back in the cylinder and maybe scratching the cylinder wall. Then you're right back where you started.