Like that young boy, many people are unclear about the nature of the gift of the Holy Ghost. There are many things we don't know, but we do know that it is a precious spiritual blessing that is given after baptism by the laying on of hands, a priesthood ordinance that has been restored in The Church of Jesus Christ of Latter-day Saints.
Barry Bickmore in his book, Restoring the Ancient Church, briefly discusses the gift of the Holy Ghost in Chapter 4 based on a few things we know from early Christianity (for the references, see the online book):
The Laying on of Hands for the Gift of the Holy GhostThis spiritual gift is, of course, subjective and personal. The comfort and guidance provided occurs at a personal level and is dependent on our willingness and ability to listen to the whisperings of "the still small voice" that comes from God. When we are living according to the teachings of Christ, that is when we are most likely to experience the blessings of the gift of the Holy Ghost.
One more issue needs to be addressed in connection with baptism. Namely, the ordinance of baptism was not originally just a dunking. At first it included both immersion and the laying on of hands for the reception of the Holy Ghost, and only later did baptism become two separate rites. Likewise, Joseph Smith preached: "Baptism by water is but half a baptism, and is good for nothing without the other half--that is, the baptism of the Holy Ghost."106
Laying on of hands always accompanied baptism in the New Testament. For example, after Philip preached to the Samaritans and baptized quite a number of them, the Apostles came and conferred the Gift of the Holy Ghost.Now when the Apostles which were at Jerusalem heard that Samaria had received the word of God, they sent unto them Peter and John: Who, when they were come down, prayed for them, that they might receive the Holy Ghost: (For as yet he was fallen upon none of them, only they were baptized in the name of the Lord Jesus.) Then laid they their hands on them, and they received the Holy Ghost. (Acts 8:14-17)Certain post-Apostolic writers were anxious to preserve the form and meaning of these rites. Tertullian, for example, both confirmed that baptism was necessary and clearly defined the two parts of the ordinance:When, however, the prescript is laid down that "without baptism, salvation is attainable by none" (chiefly on the ground of that declaration of the Lord, who says, "Unless one be born of water, he hath not life"), there arise immediately scrupulous, nay rather audacious, doubts on the part of some . . . . Not that in the waters we obtain the Holy Spirit; but in the water, under (the witness of) the angel, we are cleansed, and prepared for the Holy Spirit . . . . In the next place the hand is laid on us, invoking and inviting the Holy Spirit through benediction.107Cyprian not only recorded the form of the rites, he identified baptism and the laying on of hands with being "born of water and the Spirit":[After the baptisms by Philip in Samaria] that which was needed was performed by Peter and John; viz., that prayer being made for them, and hands being imposed, the Holy Spirit should be invoked and poured out upon them, which now too is done among us, so that they who are baptized in the Church are brought to the prelates of the Church, and by our prayers and by the imposition of hands obtain the Holy Spirit, and are perfected with the Lord's seal.108For then finally can they be fully sanctified, and be the sons of God, if they be born of each sacrament; since it is written, "Except a man be born again of water, and of the Spirit, he cannot enter into the kingdom of God."109And Bishop Cornelius of Rome disapproved of the practice of baptizing without laying on hands, for without it, how could one receive the Holy Ghost? It would only be "half a baptism," as Joseph Smith said.Being delivered by the exorcists, he fell into a severe sickness; and as he seemed about to die, he received baptism by affusion, on the bed where he lay; if indeed we can say that such a one did receive it. And when he was healed of his sickness he did not receive the other things which it is necessary to have according to the canon of the Church, even the being sealed [laid hands on] by the bishop. And as he did not receive this, how could he receive the Holy Spirit? . . .110Baptism and the laying on of hands for the reception of the Holy Ghost are necessary to enter the Kingdom of God. Joseph Smith not only got the concept right, however, he also restored the proper forms of the ordinances and the knowledge that a merciful and just God would never condemn little children for sins they never committed.
The Holy Ghost is a key means through which God gives personal revelation to His sons and daughters on earth. The Holy Ghost testified of Christ and teaches of of Him and helps us remember Him and know what we should do (John 14:26; 15:26). It is only though personal revelation that we can know that Jesus is the Christ and that the Gospel of Jesus Christ is true. This leads us to the much-derided LDS concept of a "testimony" through personal revelation, but as foreign as that concept is to the world, it is remarkably consistent with New Testament Christianity.
So returning to the question from a child in Missouri, what gift do you give a ghost? I suppose what the Holy Ghost wants most from us is that we have faith in Jesus Christ and strive to follow Him in a covenant relationship. The Holy Ghost testifies of Christ and seeks to bring us unto Him that we may have eternal life, the greatest gift of all.