The New Testament was all written by eight different men in the years following the birth, life, ministry, death, resurrection, and ascension of our Lord Jesus Christ. Three of those men were eye witnesses (Matthew, Peter and John) and two were brothers of Jesus (James and Jude). Many believe the writing of the different books and letters was complete by the time John wrote the book of Revelation, which would then be the last book written. The page I linked to postulates that John collected the books and letters, since he was the last living apostle, and was uniquely qualified to canonize the Scriptures, being of the Aaronic (Levitical priest) blood line.