Just to clear things up: usually when it asks to explain the importance you link the four characteristics of religion (beliefs, ethics, sacred texts/writings, rituals/ceremonies) and at the same time, give relevant details specific to the question. So in your question above, here's a rough outline (in dot-point form) of what I'd do when forming my answer...
Outline (very simple and general terms) the death of Jesus: Jesus taught a very radical new message: to love God, love others and love yourself. He was killed for this innovative view as he was seen as a threat to the Jewish religious tradition. He was put to death under Pontius Pilate (Roman official) and was crucified (nailed to a cross). He was taken down from the cross and buried in a tomb. There he stayed for three days.
Outline the resurrection of the Jesus: At the daybreak of Sunday, two days after Jesus had died on the Cross, Mary of Magdala and Mary the mother of James went to the tomb where he was buried. However, when they arrived it was empty and the stone had been pulled back to open up the tomb. There, an angel told the two women Jesus had resurrected. In awe and amazement, the women hurried back to tell the disciples of what had occurred. Upon the women’s encounter with Jesus he ate a fish to prove his humanity (i.e. that he wasn’t a Ghost). Thus, it was reported that Jesus rose from the dead.
Importance for Christians: the death and resurrection is one of the foundational doctrines on which Christianity is formed (i.e. it is a core belief). The belief provides a firm basis for Christian ethical teachings and rituals and ceremonies and can be read about in the sacred text of the Bible (the Gospels of the New Testament to be exact). The four gospels of the Bible tell the story of how Jesus was killed and then rose from the dead. Due to the four gospel writers, it was an event recounted more than once, and the different descriptions put a different emphases on certain aspects of the event and the subsequent messages God intended. For example, [find a two Gospel references (from two different Gospel writers) quoting the important bits about Jesus' death and resurrection, it could be as simple as 'he was nailed to the cross'). These different perspectives not only highlight the ultimate importance it has on Christian historical teachings. The text strongly implies God's key messages such as sacrifice, atonement, triumph over death, reconciliation and the revelation of God's message. This message is one of God's ulimate love: God has given us life forever because he loves us. To attain salvation, it is up to humanity to keep a right relationship with God by loving him, loving others and loving themselves. This is the most important ethical teaching for Christians (love God, others and yourself), even today. For many Christians it is hard to live out this value of unconditional love. However, through the sacred ritual of the Eucharist Christians are reminded of the universal and timeless nature of God's message. The Eucharist is a symbolic action performed by Christians concerning the belief that Jesus died and rose from the dead in order to provide forgiveness and salvation to all of humanity. The Eucharist is consecrated and consumed by Christians to provide them with Jesus’ body and blood (the real presence of the bread and wine). It is in this sense that humanity must go live out’s Christ’s great moral message, that is: to live a Christian life; to love God, others and yourself. During the Church ceremony, sacred words, taken from updated, contemporary texts are said by the people including “we lift them (our hearts) up to the Lord,” and “it is right to give Him (God) thanks and praise.” These quotes emphasise the fact that religion has become a lively and integral part of many Christians’ lives. Ulitimately, it is the single, powerful event of Jesus' death, but more importantly, his resurrection that is paramount to the lives of the adherents of Christianity. The event is written in the sacred text of the Gospels (New Testament of the Bible). It summarisies core Christian beliefs, provides ethical guidelines for believers and forms the basis of faith when practising rituals and ceremonies such as the Eucharist.
This is ALL my work so read it carefully and DON'T TRUST a single word of it.
P.S The massive paragraph is all linked. But I am sure it could be broken up into much smaller paragraphs.