Yes, the simple mechanical advantage I understand. But what I need to know is if yoou have a large wooden beam, how do you factor the weight of that beam.

I have a hickory beam that will have 9 feet of working length, and the weight of that working portion is about 220 pounds

considering it a class 2 lever, how do you factor that 20 pounds? because it cannot all accurately be considered a force applied on the far end.