Matthew 3

John the Baptist is introduced as a person expected in the Old Testament to prepare the way for the coming Messiah (means "anointed one," the OT was the anointed one.) John is Jesus' cousin. Matthew 3:3 is referencing Isaiah 40:3. John was calling for people to turn from their sins and be baptized as a sign of new life. Baptism was a new idea at the time. This is different from your baptism, which is for forgiveness and empowerment by Jesus. John's only offer forgiveness. John specifically targets the religious leaders of the day as most needing this baptism.

Jesus is baptized, not because he sinned but because God asked of this for all. God tells all present that he is pleased with Jesus. Notice that Jesus went up out of the water. No one knows if baptism was full immersion of the person or that Jesus was just standing in water when he was baptized. The importance is that water is used. How wet we get is not really addressed in this passage.