Pope Francis: St Peter's crowds hear Angelus prayer
Pope Francis has delivered the Angelus prayer and blessing before a crowd of many thousands gathered in St Peter's Square in Rome.
The Pope also delivered off-the-cuff remarks, about God's power to forgive, instead of reading a written speech.
It was the Pope's second official appearance before the general public since he was elected on Wednesday.
Earlier, he celebrated his first Sunday mass as pontiff in the Vatican's small and simple parish church.
Before he entered the church, chosen instead of St Peter's Basilica, Pope Francis greeted well-wishers who had lined up outside a nearby Vatican gate shouting "Francesco" - his name in Italian.
The former Argentine cardinal Jorge Mario Bergoglio, 76, was the surprise choice of cardinals meeting in Rome to pick the successor to the retiring Benedict XVI.
But correspondents say he has been quick to stamp his own style on the papacy.
Speaking on Saturday, Pope Francis emphasised that he wanted "a poor Church, for the poor".
At the end of the Sunday Mass, he waited outside the church and greeted people as they left, like a parish priest, asking many of them to, "pray for me".
Later, just a few minutes after delivering the Angelus, Pope Francis sent his first Tweet as pontiff, writing: "Dear friends, I thank you from my heart and I ask you to continue to pray for me. Pope Francis."
First impressions of the new Pope from the faithful on St Peter's Square have been favourable.
"He uses simple words for all people," said policeman Claudio, who was born in Rome.
"Plus he's Hispanic and so closer to the Italians."
Daniella from Montreal welcomed Pope Francis's election as "a nice surprise".
"This Pope has a warmth about him - you feel he is talking directly to you," she told the BBC.
Linda Walsh - a grandmother from Texas - said she was glad a Jesuit who had taken a vow of poverty had been chosen to lead the Church.
"The Church has its problems with issues like money laundering and I think Pope Francis will clean house," she said.
"He has the humility and braveness that's needed."
The new Pope's tone is very different to that of his predecessor, the BBC's Michael Hirst, in Rome, says.
His style is pastoral, he teaches by anecdote and speaks off the cuff with ease, in contrast to the theological sermonising of Pope Benedict, our correspondent says.
Benedict - now Pope emeritus Benedict - became the first pontiff in 600 years to abdicate last month when he said his age, 85, and health meant he could no longer continue in the job.