What does the Bible say about baptism ?

Do you really need to be baptized to go to heaven ? 

John the Baptist was born by a miracle of God from his old barren mother Elizabeth. His father was Zacharias and they were descended from a priestly family of Aaron.

Luke 1:5-7 New International Version (NIV)
In the time of Herod king of Judea there was a priest named Zechariah, who belonged to the priestly division of Abijah; his wife Elizabeth was also a descendant of Aaron. 6 Both of them were righteous in the sight of God, observing all the Lord’s commands and decrees blamelessly. 7 But they were childless because Elizabeth was not able to conceive, and they were both very old.

John was born to serve a specific purpose in life. He was to prepare the peoples for the coming of Jesus. He must have started preaching quite young as he was only 6 months older than Jesus. He was also blessed by God and be filled with the Holy Spirit even before being born. This is how he knew the Word as an infant. 

Zechariah was in the temple when he learned of his new to be son. The angel Gabriel came to him and told him the good news.

Luke 1:11-17 Then an angel of the Lord appeared to him, standing at the right side of the altar of incense. 12 When Zechariah saw him, he was startled and was gripped with fear. 13 But the angel said to him: “Do not be afraid, Zechariah; your prayer has been heard. Your wife Elizabeth will bear you a son, and you are to call him John. 14 He will be a joy and delight to you, and many will rejoice because of his birth, 15 for he will be great in the sight of the Lord. He is never to take wine or other fermented drink, and he will be filled with the Holy Spirit even before he is born.

John was to bring back people of Israel to God. The Jews had strayed from the ways of Abraham. They needed to repent so they could enter the Kingdom of God.

John the Baptist knew that he had been called by God to fulfill the prophecy of Isaiah: Mathew 3:3 (mouseover text) , quoting Isaiah 40:3 Read this link for context.

John would baptize people in water and preach repentance. He would baptize Jesus. Paving the way for the Messiah.

There are many verses having to do with baptism. It is a visual thing meant to show your repenting and changing your ways to be godly. The water symbolizes washing away your sins.

Should you be baptized first and then repent ? 

That is a question that seems to have two answers. Some say yes and some say no. Either way you go I would guess you will be just fine. I think repenting allows your sins to be forgiven and thus should be done first and then baptism to show others you have changed your ways and now walk with God.

Matthew 28:18-20
“And Jesus came and spake unto them, saying, All power is given unto me in heaven and in earth. Go ye therefore, and teach all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Ghost: Teaching them to observe all things whatsoever I have commanded you: and, lo, I am with you always, even unto the end of the world. Amen.”

There is a very good in depth article written about baptism at Bible Truth . Very good read.