How do I tighten flywheel on my 92 buick century special?

I'm assuming that you are getting a rattle at idle or at some range of rpm? Also the flywheel bolts you're referring to would be the ones connecting the torque converter to the flywheel? Most cars have a cover plate at bottom of the transmission next to engine (inspection plate). You'll be able to see those bolts once its removed. However! If they have been loose, they WILL elongate the hole on flywheel. Tightening them usually doesn't last very long. If that is the case then only option is to pull transmission and replace the flywheel.