"Penance is a sacrament of the New Law instituted by Christ in which forgiveness of sins committed after baptism is granted through the priest's absolution to those who with true sorrow confess their sins and promise to satisfy for the same. It is called a "sacrament" not simply a function or ceremony, because it is an outward sign instituted by Christ to impart grace to the soul. As an outward sign it comprises the actions of the penitent in presenting himself to the priest and accusing himself of his sins, and the actions of the priest in pronouncing absolution and imposing satisfaction. This whole procedure is usually called, from one of its parts, "confession", and it is said to take place in the "tribunal of penance", because it is a judicial process in which the penitent is at once the accuser, the person accused, and the witness, while the priest pronounces judgment and sentence. The grace conferred is deliverance from the guilt of sin and, in the case of mortal sin, from its eternal punishment; hence also reconciliation with God, justification. Finally, the confession is made not in the secrecy of the penitent's heart nor to a layman as friend and advocate, nor to a representative of human authority, but to a duly ordained priest with requisite jurisdiction and with the "power of the keys", i.e., the power to forgive sins which Christ granted to His Church."
This is from Catholic Encyclopedia. For those of us who are not officially part of the Church, what does this mean for us? Is penance what the protestants call repenting? If I can not go to confession, then what do I do?