How can the laity help the Church in her care of souls? The laity can help the Church in her care of souls by leading lives that will reflect credit on the Church, and by cooperating with their bishops and priests, especially through Catholic Action.
Behave yourselves honorably among the pagans; that, whereas they slander you as evildoers, they may, through observing you, by reason of your good works glory God in the day of the visitation. (I Peter 2:12)
What is Catholic Action? Catholic Action is the active participation of the laity in the apostolate of the Church under the guidance of the hierarchy.
In what ways can the laity participate actively in the apostolate of the Church? The laity can participate actively in the apostolate of the Church when they arouse the interest of non-Catholics in the Catholic faith; promote high standards in the press, motion pictures, radio and television; take part in the activities of Catholic societies and organizations; represent, under proper direction, the Church's position in speaking and writing; and go as lay missionaries to foreign lands.
Further reading: CCC 898-910