"Only God forgives sins. Since he is the Son of God, Jesus says of himself, "The Son of man has authority on earth to forgive sins" and exercises this divine power: "Your sins are forgiven." Further, by virtue of his divine authority he gives this power to men to exercise in his name."

Catechism of the Catholic Church
# 1441

The Sacrament of Reconciliation or Confession

20 minutes before the start of each Sunday  Mass

† Guide to making a good Confession - click for details