To receive the partial indulgence, all you need to do is pray for the success of WYD and the three "normal" things needed for an indulgence -- confession, communion and praying for the Pope's intentions.
As the Catechism reminds us, an indulgence is a remission before God of the temporal punishment due to sins whose guilt has already been forgiven. In other words, even though our sin is forgiven, there remain temporal punishment (i.e. purgatory). An indulgence pardons us from the remaining temporal punishment. An indulgence can be "partial"--removing some of the time--or "plenary"--removing all of our temporal punishment.
This is one of those aspects of our faith that not everyone will get excited about and admittedly, it isn't the easiest concept to grasp, but one of the various options the Church gives to us to help us to become closer to God.
You can read more about the Apostolic Penitentiary, the Vatican office whose only job is to handle matters of indulgences and issues of the "internal forum" (i.e. stuff to be talked about under the seal of confession) at their website.
Below is the news brief from the Vatican Information Service:
PLENARY INDULGENCE FOR 23RD WORLD YOUTH DAY
VATICAN CITY, 5 JUL 2008 (VIS) - According to a decree made public today and signed by Cardinal James Francis Stafford and Bishop Gianfranco Girotti, O.F.M. Conv., respectively penitentiary major and regent of the Apostolic Penitentiary, Benedict XVI will grant the faithful Plenary Indulgence to faithful who "gather at Sydney, Australia, in the spirit of pilgrimage" to participate in celebrations for 23rd World Youth Day, and Partial Indulgence to "all those who, wherever they are, will pray for the spiritual goals of this meeting and for its happy outcome".
The English-language decree reads: "The youth meeting held in the year 2005 in Cologne, offered the Apostolic Penitentiary an opportune occasion, with the authority of the Supreme Pontiff, to open wide to youth the spiritual treasures of the Church, with the aim of gathering singular fruits of sanctification.
"Hence, this year, from 15 to 20 July, in Sydney, 'in the great southern land of the Holy Spirit' (according to the expression of John Paul II), will celebrate the 23rd World Youth Day, with the theme: 'You will receive power when the Holy Spirit has come upon you; and you will be my witnesses'.
"Indeed", the decree adds, "young people gathered around the Vicar of Christ will participate in the sacred functions and above all have recourse to the Sacraments of Reconciliation and the Eucharist. In the Sacraments received with a sincere and humble heart, they will earnestly desire to strengthen themselves in the Spirit, and, confirmed by the Chrism of salvation, will openly witness the faith before others even to the ends of the earth. May God grant that the very presence of the Supreme Pontiff among the young people gathered in Sydney express and render it such".
The indulgences may be gained in the following ways:
"The Plenary Indulgence is granted to the faithful who will devotedly participate at some sacred function or pious exercise taking place during the 23rd World Youth Day, including its solemn conclusion, so that, having received the Sacrament of Reconciliation and being truly repentant, they receive Holy Communion and devoutly pray according to the intentions of His Holiness.
"The Partial Indulgence is granted to the faithful, wherever they are during the above-mentioned meeting, if, at least with a contrite spirit, they will raise their prayer to God the Holy Spirit, so that young people are drawn to charity and given the strength to proclaim the Gospel with their life.
"So that all the faithful may more easily obtain these heavenly gifts, priests who have received legitimate approval to hear sacramental confessions, should welcome them with a ready and generous spirit and suggest public prayers to the faithful, for the success of the same World Youth Day".
PENT/DECREE
INDULGENCES/WYD
