Christians are named after Jesus Christ. In Jesus’ own time, he would likely have been known as Jesus of Nazareth, or perhaps Jesus “Bar Joseph” i.e. “Son of Joseph.” Christians refer to him as Jesus Christ because the title “Christ” was applied to him very early in the history of Christianity. “Christ” is the Greek equivalent of “Messiah,” and means “anointed one.” Basically this means that we believe Jesus is the predicted king in the line of David, the ideal Jewish king.
However, we believe Jesus is more than just an earthly king. He is, for Christians, much more. Christians believe that Jesus is God incarnate, i.e. God in the flesh. This means that Christians believe that the God of the cosmos became uniquely human in the person of Jesus Christ. Thus, Jesus Christ is true God. However, we also believe he is true human, which is to say he was genuinely human as well.
Because he was fully God and fully human, his teachings were the very teachings of God. Jesus was born of a Virgin (Mary) and became a travelling teacher/preacher when he was around 30. This was the public ministry of Jesus. Jesus revealed the way to God, and taught us how to love God and neighbor. After ministering for three years, he increasingly ran afoul of the authorities. This led to his crucifixion and death on Good Friday.
Three days later Christians believe Jesus was raised from the dead, which is to say, he is no longer dead, but is living. Forty days after his resurrection, he returned to the Father in heaven, an event called the Ascension, celebrated 40 days after Easter Sunday.