You need to go buy or rent(from any auto zone, advanced auto etc) a compression tester. You will take out your spark plug, screw in the tester then hold the throttle wide open with the ignition switch off and kick it till the gauge doesn't go any higher. Record that reading and do it again to make sure the numbers are close to the same. Report back that number. Be sure to hit the air release button on the comp tester before you do it a second time.You should be able to buy a comp tester for $20-30 and if you rent it you just pay them their rental price. When you return it they will give you all your money back. Basically paying for the tool in case you don't return it and when you return it it becomes a free tool rental.