Authorship and Origin:

The letter states that it is from Paul, writing from prison, however some commentators are not convinced due to it's difference in style, different use of words (such as 'church'), and theological differences from other Pauline letters. Due to these controversies, the date of the authorship of this letter is not clear, although it was probably written before 95 A.D., perhaps as early as 62 A.D.. If it wasn't written by Paul himself, it was certainly written by a Jewish Christian who was a devoted admirer of Paul.

Overview and Significant sections

The book does not have the form of a letter in the strict sense, since it does not address any local issues or problems, or a particular groups of Christians. It may have been a compilation of Pauline texts designed to introduce Pauline theology, and as such was circulated to a number of churches for teaching.

Significant sections:

For more detailed study:
Read Chapter 1. (the entire book is available here.)
The Concise Matthew Henry Commentary on this book.
bible.org study of this book.
the World Wide Study Bible has Dictionary, Commentary, Scripture and sermons available on this book.