Archbishop Fulton Sheen says, "The greatest untapped treasures are of spiritual power and to be found in the Christian laity. It is mainly through the laity that the Church enters into the world."

One of the first examples of Confirmation in the early Church is in the book of Acts: 

Acts 8:14- 19 "Now when the apostles in Jerusalem heard that Samaria had accepted the word of God, they sent them Peter and John, who went down and prayed for them, that they might receive the holy Spirit, for it had not yet fallen upon any of them; they had only been baptized in the name of the Lord Jesus.
Then they laid hands on them and they received the holy Spirit.   When Simon saw that the Spirit was conferred by the laying on of the apostles’ hands, he offered them money and said, 'Give me this power too, so that anyone upon whom I lay my hands may receive the holy Spirit.'" 

Philip had baptized these people in Samaria, but he did not have the power to confirm them which necesitated that Peter and John head all the way from Jerusalem to pray for the Holy Spirit upon those who had been baptized. 

Dr. Brant Pitre says that many Christians do not believe in the Sacrament of Confirmation because the word "Confirmation" does not appear in the Bible.  However, the reality is that Confirmation - the laying on of hands done only by the Apostles and their successors for an outpouring of the Holy Spirit - does indeed appear in Scripture. 

Confirmation confirms the grace we have received in Baptism.  In Baptism we become children of God, but in Confirmation we become His witnesses in the world.  A simple way to say this would be, "In Baptism we are made God's family, in Confirmation we are made for mission."  Jesus baptized and gave us his Body and Blood in the Eucharist. He died on the cross and rose again. There were eye-witnesses to Jesus' life, miracles, and Resurrection. Jesus sent those witnesses to tell the world about Him. We are His witnesses too - we can tell how Jesus' has transformed our own lives and share the Gospel that was taught to us!  However, Jesus knew  being a witness would be difficult.  He knew that we could not face the challenges of rejection, persecution, and even death alone. We needed a helper - Jesus calls the Holy Spirit the Advocate and promises we will not be alone. 

John 4: 15-28: “If you love me, you will keep my commandments. And I will ask the Father, and he will give you another Advocate to be with you always, the Spirit of truth, which the world cannot accept, because it neither sees nor knows it. But you know it, because it remains with you, and will be in you.  I will not leave you orphans; I will come to you. In a little while the world will no longer see me, but you will see me, because I live and you will live. On that day you will realize that I am in my Father and you are in me and I in you. Whoever has my commandments and observes them is the one who loves me. And whoever loves me will be loved by my Father, and I will love him and reveal myself to him.” Judas, not the Iscariot, ^* said to him, “Master, [then] what happened that you will reveal yourself to us and not to the world?” Jesus answered and said to him, “Whoever loves me will keep my word, and my Father will love him, and we will come to him and make our dwelling with him. Whoever does not love me does not keep my words; yet the word you hear is not mine but that of the Father who sent me...I have told you this while I am with you. The Advocate, the holy Spirit that the Father will send in my name—he will teach you everything and remind you of all that [I] told you."