The Baptism of the Holy Spirit
John 7:37-39 (NKJV)
The Promise of the Holy Spirit
 On the last day, that great day of the feast, Jesus stood and cried out, saying, “If anyone thirsts, let him come to Me and drink.  “He who believes in Me, as the Scripture has said, out of his heart will flow rivers of living water.”  But this He spoke concerning the Spirit, whom those believing* in Him would receive; for the Holy* Spirit was not yet given, because Jesus was not yet glorified.
John 16:7 (NKJV)
7 Nevertheless I tell you the truth. It is to your advantage that I go away; for if I do not go away, the Helper will not come to you; but if I depart, I will send Him to you.
John 16:7 (KJV)
7 Nevertheless I tell you the truth; It is expedient for you that I go away: for if I go not away, the Comforter will not come unto you; but if I depart, I will send him unto you.
THE WORD MEANS...
Beneficial, expedient, useful, helpful, worthwhile, advisable, profitable, good for you, Advantage.
John 16:7 (AMP)
7 However, I am telling you nothing but the truth when I say it is profitable (good, expedient, advantageous) for you that I go away. Because if I do not go away, the Comforter (Counselor, Helper, Advocate, Intercessor, Strengthener, Standby) will not come to you [into close fellowship with you]; but if I go away, I will send Him to you [to be in close fellowship with you].
We see that we need the Holy Spirit.
Acts 1:4-8 (NKJV)
The Holy Spirit Promised
 And being assembled together with them, He commanded them not to depart from Jerusalem, but to wait for the Promise of the Father, “which,” He said, “you have heard from Me;  “for John truly baptized with water, but you shall be baptized with the Holy Spirit not many days from now.”  Therefore, when they had come together, they asked Him, saying, “Lord, will You at this time restore the kingdom to Israel?”  And He said to them, “It is not for you to know times or seasons which the Father has put in His own authority.  “But you shall receive power when the Holy Spirit has come upon you; and you shall be witnesses to Me* in Jerusalem, and in all Judea and Samaria, and to the end of the earth.”
How did they receive
Acts 2:1-4 (NKJV)
Coming of the Holy Spirit
[2:1] When the Day of Pentecost had fully come, they were all with one accord* in one place.  And suddenly there came a sound from heaven, as of a rushing mighty wind, and it filled the whole house where they were sitting.  Then there appeared to them divided tongues, as of fire, and one sat upon each of them.  And they were all filled with the Holy Spirit and began to speak with other tongues, as the Spirit gave them utterance.
Is this the evidence of the in filling of Holy Spirit of early church
Acts 10:34-48 (NKJV)
Preaching to Cornelius’ Household
 Then Peter opened his mouth and said: “In truth I perceive that God shows no partiality.  “But in every nation whoever fears Him and works righteousness is accepted by Him.  “The word which God sent to the children of Israel, preaching peace through Jesus Christ—He is Lord of all—  “that word you know, which was proclaimed throughout all Judea, and began from Galilee after the baptism which John preached:  “how God anointed Jesus of Nazareth with the Holy Spirit and with power, who went about doing good and healing all who were oppressed by the devil, for God was with Him.  “And we are witnesses of all things which He did both in the land of the Jews and in Jerusalem, whom they* killed by hanging on a tree.  “Him God raised up on the third day, and showed Him openly,  “not to all the people, but to witnesses chosen before by God, even to us who ate and drank with Him after He arose from the dead.  “And He commanded us to preach to the people, and to testify that it is He who was ordained by God to be Judge of the living and the dead.  “To Him all the prophets witness that, through His name, whoever believes in Him will receive remission of sins.”
The Holy Spirit Falls on the Gentiles
 While Peter was still speaking these words, the Holy Spirit fell upon all those who heard the word.  And those of the circumcision who believed were astonished, as many as came with Peter, because the gift of the Holy Spirit had been poured out on the Gentiles also.  For they heard them speak with tongues and magnify God. Then Peter answered,  “Can anyone forbid water, that these should not be baptized who have received the Holy Spirit just as we have?”  And he commanded them to be baptized in the name of the Lord. Then they asked him to stay a few days.
Acts 19:1-6 (NKJV)
[19:1] And it happened, while Apollos was at Corinth, that Paul, having passed through the upper regions, came to Ephesus. And finding some disciples  he said to them, “Did you receive the Holy Spirit when you believed?” So they said to him, “We have not so much as heard whether there is a Holy Spirit.”  And he said to them, “Into what then were you baptized?” So they said, “Into John's baptism.”  Then Paul said, “John indeed baptized with a baptism of repentance, saying to the people that they should believe on Him who would come after him, that is, on Christ Jesus.”  When they heard this, they were baptized in the name of the Lord Jesus.  And when Paul had laid hands on them, the Holy Spirit came upon them, and they spoke with tongues and prophesied.
What are some of the benefits
1 Corinthians 14:2 (NKJV)
 For he who speaks in a tongue does not speak to men but to God, for no one understands him; however, in the spirit he speaks mysteries.
1 Corinthians 14:4 (NKJV)
 He who speaks in a tongue edifies himself, but he who prophesies edifies the church.
1 Corinthians 14:14-15 (NKJV)
 For if I pray in a tongue, my spirit prays, but my understanding is unfruitful.  What is the conclusion then? I will pray with the spirit, and I will also pray with the understanding. I will sing with the spirit, and I will also sing with the understanding.
1 Corinthians 14:18 (NKJV)
 I thank my God I speak with tongues more than you all;
1 Corinthians 14:37-40 (NKJV)
 If anyone thinks himself to be a prophet or spiritual, let him acknowledge that the things which I write to you are the commandments of the Lord.  But if anyone is ignorant, let him be ignorant.*  Therefore, brethren, desire earnestly to prophesy, and do not forbid to speak with tongues.  Let all things be done decently and in order.
How do we receive
Luke 11:13 (NKJV)
13 “If you then, being evil, know how to give good gifts to your children, how much more will your heavenly Father give the Holy Spirit to those who ask Him!”