2000 Oldsmobile Achieva Engine Missfires

I was with my Friend deciding if it would be wise to buy a certian car. I was listening to the engine while it was running and it appeared that the engine may have a misfire. my friend and I both decide that if it is only an ignition problem, my friend would buy the car.

Could you help explain in detail some simple testing I can do to find out if the problem causing the miss is more serious ( Bad piston, Bad valve etc.) The only tools that were given to me are a screwdriver, pliers, and a test light.