The Bible is written and arranged into 66 Books by 40 Authors and according to literature type.
The Old Testament period ended approximately 400 years prior to the time of the New Testament writings, however the books within each occurred at a varying times. For example, the events of Ezra and Nehemiah took place near the end of the Old Testament period, yet the books are listed before Job which is believed to be the oldest book in the bible in terms of when it was actually penned, and the events of which took place long before those in Ezra and Nehemiah.
Another important note, is that within each section of writing most books are in basic chronological order. For example, in the Old Testament prophets, Isaiah lived before Jeremiah. In the Books of Moses, Genesis took place first and Deuteronomy took place last.