What is the New Testament?
The New Testament contains all the revelations which God gave after the coming of Jesus Christ into the world just as the Old Testament are those revelations which God gave us prior to Jesus coming.
What books make up the New Testament?
Matthew, Mark, Luke, John, Acts
Letters
Romans, 1 Corinthians, 2 Corinthians, Galatians, Ephesians, Philippians, Colossians, 1 Thessalonians, 2 Thessalonians, 1 Timothy, 2 Timothy, Titus, Philemon, Hebrews, James, 1 Peter, 2 Peter, 1 John, 2 John, 3 John, Jude
Prophecy
In what order were these books first written?
It would appear that James was the first book or, in this case, letter to be written. Warfield provides the following order:
Plausible dates.