Herod the Tetrarch put John the Baptist in prison. Why did he do this?

Herod was in an adulterous relationship with Herodias. She was married to Herod’s brother Phillip.

Source: Matthew 14:3-5, Mark 6:17-20, Luke 3:18-20

John got his name from Baptizing many people. Was this a Christian baptism?

It was not the baptism of John was a baptism of repentance. It was also lacking in the Holy Spirit. Which did not come until Pentecost.

Source: Mark 1:4, Acts 19:2-6

Who told Zacharias that he would have John the Baptist as his son?

The angel Gabriel told him the he would have a son. Zacharias did not believe him and was mute until John’s birth and naming.

Source: Luke 1:13-20

Who were the parents of John the Baptist?

John the Baptist had Zacharias and Elisabeth as his parents.

Source: Luke 1:5-13