Jesus said "I and my Father are one" (John 10:30). Jesus, also called the "Word," existed with God from the beginning. Creation took place through Jesus, as explained in John 1:1-3:
In the beginning was the Word, and the Word was with God, and the Word was God. The same was in the beginning with God. All things were made by him; and without him was not any thing made that was made.
Here are a few other verses showing Jesus existed with the Father even before the creation, and was the One through whom creation took place:
I have glorified thee on the earth: I have finished the work which thou gavest me to do. And now, O Father, glorify thou me with thine own self with the glory which I had with thee before the world was. (spoken by Jesus, recorded in John 17:5)
God, who at sundry times and in divers manners spake in time past unto the fathers by the prophets, Hath in these last days spoken unto us by his Son, whom he hath appointed heir of all things, by whom also he made the worlds (written by the apostle Paul, in Hebrews 1:1,2)
Unto me, who am less than the least of all saints, is this grace given, that I should preach among the Gentiles the unsearchable riches of Christ; And to make all men see what is the fellowship of the mystery, which from the beginning of the world hath been hid in God, who created all things by Jesus Christ (Paul, in Ephesians 3:8,9)
For by him were all things created, that are in heaven, and that are in earth, visible and invisible, whether they be thrones, or dominions, or principalities, or powers: all things were created by him, and for him: And he is before all things, and by him all things consist. And he is the head of the body, the church: who is the beginning, the firstborn from the dead; that in all things he might have the preeminence. (Paul, in Colossians 1:16-18)
Even in the Garden of Eden we find reference to the Father and the Word together: note the use of "us" in these verses:
And God said, Let us make man in our image, after our likeness: and let them have dominion over the fish of the sea, and over the fowl of the air, and over the cattle, and over all the earth, and over every creeping thing that creepeth upon the earth. (Genesis 1:26)
And the LORD God said, Behold, the man is become as one of us, to know good and evil: and now, lest he put forth his hand, and take also of the tree of life, and eat, and live for ever: (Genesis 3:22)
For several reasons (and according to God's plan, Rev. 13:8) the Word was made human in the form we know as Jesus: "And the Word was made flesh, and dwelt among us" (John 1:14). Jesus said of His mission to mankind: "the Father which sent me, he gave me a commandment, what I should say, and what I should speak" (John 12:49). Jesus explained "For I am come down from heaven, not to do mine own will, but the will of him that sent me." (John 6:38)
Jesus preached the gospel - the good news - of the kingdom of God. "And it came to pass afterward, that he went throughout every city and village, preaching and shewing the glad tidings of the kingdom of God: and the twelve were with him." (Luke 8:1)
Jesus also fulfilled many Old Testament prophecies, including Hosea 13:14: "I will ransom them from the power of the grave; I will redeem them from death." Jesus spoke of himself saying "the Son of man came not to be ministered unto, but to minister, and to give his life a ransom for many" (Matthew 20:28). Jesus, the sacrificial "Lamb of God," made available a payment of the death penalty we have earned for our sin:
For the wages of sin is death; but the gift of God is eternal life through Jesus Christ our Lord. (Romans 6:23)
The next day John seeth Jesus coming unto him, and saith, Behold the Lamb of God, which taketh away the sin of the world. (John 1:29)
Our sins, and the death penalty for our sins, had hopelessly alienated us from God. We were hopelessly bound to die. By paying the death penalty on our behalf Jesus opened a door for us: He made redemption to God available - if we'll repent. Redeemed (or reconciled or justified) to God, we can enter a life-long process called sanctification: He will dwell in us and lead us to grow, and overcome, and become like Him. If we continue in our sanctification, we are promised salvation: we will receive the gift of eternal life at our resurrection at His return. Because He paid the penalty for our sin on our behalf Jesus has made freedom available: freedom from the penalty for sin, and freedom from the power of the grave. Eternal life is now available for us if we are willing to repent and to seek God.
The gospel of grace is the good news that redemption, sanctification, resurrection and eternal life have been made available for us. No amount of works - good deeds - can earn redemption and eternal life: they are provided by grace, by the gift of God, but only if we choose to repent and choose to develop a right relationship with God. Jesus said "...except ye repent, ye shall all likewise perish" (Luke 13:3).
Jesus - the Word who existed with the Father from the beginning - died for our sins and remained dead for three days and three nights. He was resurrected from the dead and is now "alive for evermore":
I [am] he that liveth, and was dead; and, behold, I am alive for evermore, Amen; and have the keys of hell and of death. (Revelation 1:18)
But now is Christ risen from the dead, [and] become the firstfruits of them that slept. (1 Corinthians 15:20)
But every man in his own order: Christ the firstfruits; afterward they that are Christ's at his coming. (1 Corinthians 15:23)
Jesus' work of creation is not done. Even now it is in process, as He dwells in those whom He is sanctifying, and leads them toward spiritual completion in His image. If we are willing to obey and keep His words, He will dwell in us and manifest himself - reveal His character and His will - to us:
Jesus answered and said unto him, If a man love me, he will keep my words: and my Father will love him, and we will come unto him, and make our abode with him (John 14:23)
He that hath my commandments, and keepeth them, he it is that loveth me: and he that loveth me shall be loved of my Father, and I will love him, and will manifest myself to him (John 14:21)
After His resurrection Jesus appeared to His disciples: "And Jesus came and spake unto them, saying, All power is given unto me in heaven and in earth" (Matthew 28:18). "For the Father judgeth no man, but hath committed all judgment unto the Son: That all men should honour the Son, even as they honour the Father" (John 5:22,23). Jesus has authority over all creation, and has been authorized to judge all men. We can relate to Jesus as we would to the Father; the Father has given Jesus all power over us.
Jesus promised to return. When He returns He will fully assume over all the world the authority God has given Him. Here are a few of the many prophecies about His kingdom:
And he shall judge among the nations, and shall rebuke many people: and they shall beat their swords into plowshares, and their spears into pruninghooks: nation shall not lift up sword against nation, neither shall they learn war any more. (Isaiah 2:4)
And there was given him dominion, and glory, and a kingdom, that all people, nations, and languages, should serve him: his dominion is an everlasting dominion, which shall not pass away, and his kingdom that which shall not be destroyed. (Daniel 7:14)
Jesus will remain in full authority until His work is done, then He will return all authority back to the Father:
Then [cometh] the end, when he shall have delivered up the kingdom to God, even the Father; when he shall have put down all rule and all authority and power. For he must reign, till he hath put all enemies under his feet. The last enemy [that] shall be destroyed [is] death. (the apostle Paul, in 1 Corinthians 15:24-26)