Using religious articles for praying is not unique to Christianity or Catholics. Hindus, Jews and Muslims all use and used different artifacts to enhance some prayers. In particular, beads on a string were used by different religions. Jews for example had one hundred and fifty beads to signify the one hundred fifty Psalms of the Bible.
In Catholic tradition it is believed that St. Dominic de Guzman had a vision of Mary the mother of God in which she presented him with the first Rosary and asked him to begin reciting the Rosary instead of the Psalms. Specifically, a Hail Mary, Our Father and a Glory Be. The original Rosary was an Our Father then ten Hail Marys and ending with a Glory Be. This was referred to as a decade. At the start Christians would recite fifteen decades, but it has since been abbreviated to five.
On the crucifix, pray the Apostles Creed.
On the Next large bead, say the Our Father.
On the following three smaller beads, pray three Hail Marys.
On the chain, pray the Glory Be.
Announce the first of the Holy Mysteries; Joyful, Luminous, Sorrowful, Glorious.
On the large bead, pray the Our Father.
On the ten beads after, pray ten Hail Marys.
On the chain, pray a Glory Be.
Most Catholics will add the Prayer of Fatima after the Glory Be and before the Our Father.
Repeat steps 5-9 for a total of five decades.
In ending the Rosary say the Hail Holy Queen.
A big part of saying the Rosary is meditating on the Holy Mysteries. As mentioned above they are Joyful, Luminous, Sorrowful and Glorious. Each Mystery describes a specific time in the life of Jesus Christ. They reveal the divinity and humanity of Christ. By praying the Rosary and reflecting on the Mysteries, Christians are contemplating and reinforcing the divine nature of Jesus Christ as well as his human side. The suffering and agony he endured showed his human side. The Transfiguration, Resurrection and the Ascension proved his divine character. It emphasizes the prayer being about Christ and not a simple devotion to Mary. A Rosary can be recited in your home alone, in church or with a group. To learn more about the Catholic Rosary and read the full text of the prayers and mysteries go to howtopraytherosary.