Who assist the bishops in the care of souls? The priests, especially parish priests, assist the bishops in the care of souls.
And when they had appointed presbyters for them in each church, with prayer and fasting, they commended them to the Lord in whom they had believed. (Acts 14:22)
Who are the laity of the Church? The laity of the Church are all its members who do not belong to the clerical or to the religious state.
Further reading: CCC 897