An Indulgence in the Church is an act which removes the temporal punishment from sin making the trip from Purgatory to Heaven easier and swifter after death. In this particular case you can receive a plenary indulgence for the benefit of one person who has died by doing the following:
ALL SOULS DAY PLENARY INDULGENCE TO BE APPLIED TO A DECEASED PERSON
"A plenary indulgence, applicable ONLY to the souls in purgatory, may be obtained by those who, on All Souls Day, piously visit a church" 1) Visit a Church on All Soul's Day- Nov. 2nd- with intention of obtaining a plenary indulgence for a deceased soul that you are remembering. (Only 1 Soul remember) 2) Go to confession and Holy Communion either 20 days, before or after 11/2 3) Say the Apostles Creed and the Our Father 4) Pray for the Intentions of the Pope 5) Be detached from all sin (recite an Act of Contrition)