What chapter did tom get into a fight?

No specific reason; he loves the girls, he loves to fight, and he loves the whiskey. Are you talking about a specific fight here? Or are you talking about the man he murdered?

I think you are referring to Chapter 26. Casy, Tom and the rest of the strikers are confronted by the police. A short, heavy man with a white pick handle swings it at Casy, hitting him in the head. Tom fights with the man, and eventually wrenches the club from him and strikes him with it, killing him. Tom immediately fled the scene, crawling through a stream to get back to the cabin.