This is the most important prayer to get you started with the rosary, which is a common Catholic devotion that people often do in a group. It's nice to be able to participate.
Hail Mary, full of grace, the Lord is with thee. Blessed art thou among women, and blessed is the fruit of thy womb, Jesus. Holy Mary, Mother of God, pray for us sinners, now and at the hour of our death. Amen.
Ave Maria, gratia plena, Dominus tecum. Benedicta tu in mulieribus, et benedictus fructus ventris tui, Iesus. Sancta Maria, Mater Dei, ora pro nobis peccatoribus, nunc et in hora mortis nostrae. Amen.