Would you please tell me where I can find all the requirements of the new covenant?
It might seem overly simple, but the New Covenant is the New Testament. It is by reading it that you learn what you need to do.
"How that by revelation He made known to me the mystery (as I have briefly written already, by which, when you read, you may understand my knowledge in the mystery of Christ), which in other ages was not made known to the sons of men, as it has now been revealed by the Spirit to His holy apostles and prophets" (Ephesians 3:3-5).
"So then faith comes by hearing, and hearing by the word of God" (Romans 10:17).
If it is the New Testament then wouldn’t it have to be made before Jesus dies and if that is the case then it would have to be in the first four gospels, right?
The Old Testament was given by Moses at Mount Sinai and dedicated by the shedding of blood. "Therefore not even the first covenant was dedicated without blood. For when Moses had spoken every precept to all the people according to the law, he took the blood of calves and goats, with water, scarlet wool, and hyssop, and sprinkled both the book itself and all the people, saying, 'This is the blood of the covenant which God has commanded you'" (Hebrews 9:18-20). This took place in Exodus 24:18, yet God continued to introduce concepts and explain the covenant to the people for many years later -- both through Moses and the prophets that followed him. The Israelites were expected to follow all of God's teachings under the covenant, not just the ones given before Exodus 24:18.
In the same way, the New Testament was introduced by Jesus and dedicated by the shedding of his blood. "And for this reason He is the Mediator of the new covenant, by means of death, for the redemption of the transgressions under the first covenant, that those who are called may receive the promise of the eternal inheritance. For where there is a testament, there must also of necessity be the death of the testator" (Hebrews 9:15-16). A part of the terms of that covenant was that the apostles were to learn and teach it others, including the things that had not yet comprehended while Jesus was with them. "I still have many things to say to you, but you cannot bear them now. However, when He, the Spirit of truth, has come, He will guide you into all truth; for He will not speak on His own authority, but whatever He hears He will speak; and He will tell you things to come. He will glorify Me, for He will take of what is Mine and declare it to you. All things that the Father has are Mine. Therefore I said that He will take of Mine and declare it to you" (John 16:12-15).
Therefore the remainder of the New Testament is just as much Jesus' teachings and a part of the covenant as the four gospel accounts.