The entire Bible is inspired by God:
2 Timothy 3:16 All Scripture is breathed out by God and profitable for teaching, for reproof, for correction, and for training in righteousness
Jesus was very fluent in reading/writing scripture, yet, He in His own wisdom, thought it fit that his followers write these Gospels after his death. As such Bible through the inspiration of Holy Spirit is the revealed truth from God Himself and it includes the teachings of Jesus(who Himself is God) during His ministry which later on, inspired by Holy Spirit, were written down in four Gospels, acts and epistles by His followers. As such it is tantamount to the Word of God.
This was clearly told by Jesus:
John 16:12 “I have many more things to say to you, but you cannot bear them now. 16:13 But when he, the Spirit of truth, comes, he will guide you into all truth. For he will not speak on his own authority, but will speak whatever he hears, and will tell you what is to come. 16:14 He will glorify me, because he will receive from me what is mine and will tell it to you.
There was no need for God to reveal the Bible content to Jesus, as Jesus Himself was God Incarnate and as such the source of everything
But the next question definitely comes to mind is why four Gospels? As it would be a long answer I have answered it separately here. But briefly:
God used human authors with different backgrounds and personalities to accomplish His purposes through their writing. Each of the gospel authors had a distinct purpose behind his gospel and in carrying out those purposes, each emphasized different aspects of the person and ministry of Jesus Christ. Yet all the four Gospels are perfectly harmonious.
Historical authenticity: About historicity of Bible a lot of matter is available on this site already and I would append it with this.
Like any other historical writings there are no original documents of Bible in our possession. During its nascent years, Christianity was subjected to intense persecution. All the worldly forces were trying to wipe out Christianity by persecution and destroying all their literature. All that we have today has passed through a most turbulent period and has survived under most cruel persecution. In spite of this, we find that there are various shreds of manuscripts of NT as far as from 65AD, which is the earliest. Some information is posted here on this site.
By the time Christians could live a serene living under a favourable reigning emperor, all present day Gospels were already in use, as independent books long before they were canonised in a favourable time under a favourable reigning emperor. As seen from the table below we find that evidence for historical authenticity of New Testament is much stronger than any of the other historical books with no attempts of suppression.
Apart from this shortest timeline for the earliest copy, there are other numerous external written sources to collaborate the historical authenticity of New Testament.
Then there are some who are casting doubt on the authorship of Bible books. To summarise from this answer, the two of the gospels are ascribed to such minor characters as Mark and Luke -- neither of whom, by any accounts, were themselves neither disciples nor the eyewitnesses is solid indirect clue they were who they were. If early Christian evangelist wanted to acquire credibility for what they were writing (or forging as some claim) and preaching they would undoubtedly have attributed it to someone like Peter, Thomas or James. And precisely this was what the later second and third century Gnostic gospels did.
Further there has never been an attempt to edit or revise any of the Gospel accounts over the years nor is there any historical evidence of any attempt to concise these four gospels in to one book and say that it was written or dictated by Jesus himself. Contrary to this, there are some who claim that their scripture is directly handed down by God in physical form from heaven. However when we dig out the history, it reveals that there were authorised exercise undertaken spanning over many years, to standardise its content under different authorities, when finally the present day standardised version were accepted.