What is the Bible all about?

The Bible is God's guidebook to man.  It has 66 books (39 Old Testament--"part one" books and 27 New Testament--"part two" books) which are a roadmap of sorts, for life.

Genesis,  is the first book, starts off with the words, "In the beginning, God..." describes the creation of the world, the uniqueness and role of man and the naming of the animals.

From there it describes how man was tempted (by Satan, the devil) and sinned (or fell short of God's perfect ideal).  Even way back then this pointed to the eventual need for salvation, or someone to pay for  or cleanse us from our sin.

From there the second book in the Old Testament, EXODUS describes how the children of Israel were put into slavery, and the miracles surrounding how they were freed.

The New Testament book of Hebrews Chapter 11 gives a great summary of what the Old Testament is all about.