Roughly, each Bishop is a successor to the Apostles. As such he is in charge of his diocese, subject to the overall guidance of the Pope. the pastor of a parish is the agent of his Bishop and acts under his authority. The other priests assist the pastor in his duties.
That is the priest derives his authority from his bishop, but the bishop holds authority in his own right.
An archbishop coordinates the activities of the Bishops in his area, but has no direct authority over them.
The national council of bishops is a consultive body where bishops of the country can coordinate their activities, but have no independent power.
This is very simplified, and omits a lot of detail. Hopefully it gives you an uncluttered view.