How does Ralph gain the admiration of the other boys and what did he promise?
You sound like you are near the beginning because Ralph does not maintain the admiration of the boys.
At first, in chapter one, Ralph has the conch. This symbol of power that is used to gather, call to order, and slience the boys is a reflection of what they first admire about Ralph. He has leadership potential. But, like every other good leader, he can't do it all. So he admits he will need time to think things through but for now knows rescue and shelter are important. The promise of rescue by a signal fire earns their trust.
As time goes by, Ralph admittedly realizes that institutions he has set up are not working. The plan of a bathroom, the tending of the fire and the group effort to erect shelters all suffer and Ralph has to be a tough leader. Admiration fades.