I assume that you are talking about the confrontation that takes place between the two of them at the meeting in this chapter.
At this point, Samneric have seen the dead parachutist and have thought that he was the Beast. The boys are having this council to decide what to do about it. Piggy has the conch, but Jack tries to talk over him. Piggy protests that he has the conch and Jack basically says he does not care who has the conch.
This is where Ralph steps in. He scolds Jack, tells him to be quiet. Then he starts in on the rest of the boys. He is yelling at them about how they only want to hunt and screw around and they don't do the things necessary to try to get rescued. This gets their attention and they pay attention to him again -- they let him lead a while longer.
In Lord of the Flies, a group of school boys will learn the consequences of living without "grown ups," and how, despite the fact that they are "English; and the English are the best at everything," as Jack says in chapter two, their basic instincts are in danger of engulfing any sense of right and wrong. By chapter six, there have been developments which give the reader an uneasy sense that Ralph is losing control over the group as Jack and his hunters become a more attractive alternative, especially as the boys become more afraid of, and obsessed with, the "beast."
In chapter six, Sameneric confirm everyone's fears and relate their terrifying tale of the beast which chased them. A decision needs to be made and Jack is keen to go on a "real hunt," which annoys Ralph who can see the danger in going after it. Jack suggests that Ralph is just scared and Ralph is not shy to admit that he is. Piggy would prefer to stay away from the beast but his comments irritate both Ralph and Jack. Ralph knows something needs to be done but he always has to be the one to plan while Jack is ready to go off and hunt the beast without any concern for the littluns. Ralph gives Piggy the conch so that he can express his concerns about being left behind in case the beast comes after him and the littluns.
However, Jack has no respect for the authority of the conch and so shouts over Piggy suggesting that Piggy shouldn't be talking anyway because "It's time....to keep quiet and leave deciding things to the rest of us..." This is almost too much for Ralph who feels the "blood... hot in his cheeks." Ralph tells Jack to sit down because he does not have the conch but Jack defies Ralph and remains standing. He even goes as far as saying that finding the beast is "a hunter's job."
Piggy, who realizes that Ralph needs to assert himself, passes the conch to him and, after an "oppressive silence," Ralph speaks and points out that the beast is too clever to be tracked and also questions Jack about the importance of being rescued. Ralph regains his control and this gives him "the energy to attack." He reminds the boys, especially Jack, that the signal fire is all important. After a short while, Jack does cooperate and the confrontational situation is defused.