Jesus was the Son of God who was sent to the Earth to atone for the sins of Man. He was conceived by Mary in Bethlehem. Mary was engaged to Joseph. Mary was a virgin but she found out she was pregnant prior to her marriage with Joseph without having had sexual intercourse with any man. God sent the Holy Spirit to impregnate Mary so that His Son would be conceived of Man (miracle). That is why Jesus is both the Son of Man as well as the Son of God. Joseph wanted to withdraw his proposal to marry Mary when he found out she was pregnant with another man's child. But God sent an angel to explain this miraculous deed to Joseph.
Jesus lived as an ordinary human being until the age of 30 when he began to fulfill his mission on earth. He employed 12 helpers (disciples). He revealed himself as the Son of God through teachings about the kingdom of God and performing miracles. He claimed to be God as part of his teachings. This claim was very controversial since it was against the Jewish law. Israel was under the Roman Empire at the time of Jesus teachings. Israeli authorities asked the Roman officials to execute Jesus for breaching the law. But the Roman authorities did not find any fault with him apart from this claim and so they refused to execute him. Nonetheless the Jewish authorities persisted until they convinced an officer named Pilate in the southern part of Israel to execute Jesus.
Jesus was hanged on a cross. His hands and feet were attached to the wooden pole by nails. He died after 3 hours and was buried. 3 days later, he came back to life and continued to carry out his mission on the Earth for 40 days before ascending to His Father (God) in Heaven.
He promised to send the Holy Spirit to his disciples after He had reached Heaven. That is why his followers have his spirit (The Holy Ghost).