Acts 2: 38 Peter replied, “Repent and be baptized, every one of you, in the name of Jesus Christ for the forgiveness of your sins. And you will receive the gift of the Holy Spirit.”
Water Baptism seals the step of faith that took place in your heart with a public declaration of your decision to be a Christian. When you are immersed in the water it symbolizes that your old self, your old way of life, is now dead, just as Christ died for you. When you are raised up out of the water all the old is washed away and you are a new creation in Christ Jesus.