When I first began praying the Rosary, I wasn't quite sure how it was done. Through the internet, I found instructions for praying the Rosary and a list of the Mysteries. I learned that to pray the full traditional Rosary you say 15 "decades". a decade is composed of an Our Father, 10 Hail Marys, and a Glory Be. So in the end you have prayed 150 Hail Marys. While you are reciting the prayers you concentrate your mind on the Mysteries.
The Mysteries are an important part of praying the Rosary. In fact, they really are the prayer itself. In the Mysteries we contemplate specific parts of the life of Christ. The traditional mysteries are the Joyful, the Sorrowful and the Glorious Mysteries.
Because the full Rosary takes so long to pray, I also found that many people say only 1 "chaplet" a day. A chaplet is 5 "decades" and focuses on 1 of the 3 Mysteries. In this case there is a traditional pattern. Saturdays, Sundays, Wednesdays are the Glorious Mysteries, Mondays and Thursdays, are the Joyful Mysteries and Tuesdays and Fridays are the Sorrowful Mysteries.
So the Rosary is composed of the vocal prayers and the mental prayers of the Mysteries. The purpose of the vocal prayer is to direct the mental prayer of the Mysteries. In other words the vocal prayers help time and move the minds focus through each of the Mysteries.
I found it very helpful to pray a scriptural Rosary when I was first beginning so that I knew what to contemplate. When praying a scriptural Rosary, you read a verse from Scripture to help your mind concentrate on the Mystery at hand and then pray a Hail Mary and repeat until finished. Here are links to a good scriptural reference ( Glorious, Joyful, Sorrowful).