A little bit more on the Gospels and their history:
It's generally accepted that Mark was written first, around 50-60 AD. Luke and Matthew tell the same story as Mark, but they are significantly longer because they also relate many sayings of Jesus. Most scholars believe that they both drew from Mark and from a second source (called Q) that has since been lost. (See the Gospel of Thomas for more on Q). Matthew and Luke also add individual additions from other sources, and probably wrote between 60 and 80 AD. The Gospel of John is separate from the other three--Johannine theology is very different, as are the factual details of Jesus' life and even the specific day of his death. It is generally believed that the Gospel of John was written later than the other three, between 80 and 100 AD.