Every part of the Bible is important, because every part came from God, and every part has something to teach us about our relationship with Him. As the Bible itself says, "ALL Scripture is God-breathed and is useful for teaching, rebuking, correcting and training in righteousness" (2 Timothy 3:16, emphasis added).
At the same time, the center or heart of the Bible is Jesus Christ -- His life, death and resurrection for us. The Old Testament looks forward to His coming and tells us how God prepared the way for it (which is one reason why Jesus quoted it so much). The New Testament records Jesus' actual coming, and the difference He made in the lives of His followers after He returned to Heaven. Both parts of the Bible tell us of God's love for us.
Because Jesus is the heart of the Bible, I suggest you begin reading one of the Gospels (I often suggest John). As you read, ask God to show you who Jesus is, and what He can do in your life. You'll discover that Jesus was more than a great teacher; He was God in human flesh, who came from Heaven to save us from our sins and give us hope for the future. Could anything be more important?
Don't read, however, just to discover more information about the Bible, or about Jesus. God wants to change your life -- and He will, as you turn to Jesus and commit your life to Him. Read your Bible not only with an open mind, but with an open heart and will.