On the morning of the first day of the conclave, the cardinals should take part in the votive mass, "Pro Eligendo Papa", to be celebrated in the Basilica of St Peter's. In the afternoon, the cardinals will meet in the Pauline Chapel of the Pontifical Palace, from where they proceed "in solemn procession" to the Sistine Chapel, accompanied all the while by the chant, "Veni Creator".
In the Sistine Chapel, the Dean of Cardinals, Joseph Ratzinger, reads aloud a solemn oath after which each cardinal in turn says, with his hand on the bible, "And I, Cardinal [says his name], do so promise, pledge and swear. So help me God and these Holy Gospels which I touch with my hand".
Then the Master of Papal Liturgical Celebrations will give the famous order, "Extra Omnes" - basically everyone out, bar the cardinals.
At that point, the business of the election can begin.
Pope John Paul II decreed that, with the exception of the first day, the conclave should vote four times per day, twice in the morning and twice in the afternoon. For the first 34 ballots, a two thirds majority of the 115 Cardinal Electors (77) is required. After that, the cardinals may opt for a simple majority plus one vote.