The Bible has multiple authors, and, for that matter, multiple books.
The first problem you seem to have is, you're thinking of the Bible as a single book, when it is, in fact, a small library of different books. I can help give you a beginner's rundown of the various books and collections.
Let's start with the Old Testament, also called the Hebrew Tanahk.
The first part of the Tanakh is the Torah, or the Pentateuch, often called in English
The Five Books of Moses. These are Genesis, Exodus, Leviticus, Numbers, and Deuteronomy. Genesis is primarily prose, and tells the story of the earliest times (which ends after the story of the Tower of Babel), Abraham, Jacob, and Joseph. Exodus deals with, as the title suggests, the exodus from Egypt. The second half of Exodus details some laws, beginning with the Ten Commandments. Levitacus deals almost entirely with laws. Numbers returns to prose, and tells of the Hebrews' journey through the wilderness to the promised land (modern day Israel.) Deuteronomy is concerned once again with laws, and ends with the death and burial of Moses.
Authorship of the Torah has often been credited to Moses himself, as God dictated the entire thing to him. However, scholarship suggests multiple sources, four to be exact. (This is known as the Documentary Hypothesis.) The first source is labelled J, for Yahwist. This source uses YHWH as the name of God. The second is called E, or Elohist. This source uses Elohim to name God. (Elohim literally tranlsates out to a plural form of God. The plural is a form of glorification, I believe.) The third source is called P, or Priestly. This source is primarily concerned with the establishment of the priesthood. The fourth is D, or Deuteronomist. This source is likely the author of the entirety of Deuteronomy.
Before we continue, the Hebrew Tanakh, while containing the same books, does have a different ordering of the books than the Christian Old Testament. I will be dealing with the Hebrew Tanakh.
Next comes the Nevi'im, or Prophets. These begin with Joshua, Judges, Samuel(two books), and Kings(again, two books.) These books deal with the history of the Hebrews as they conquer(or, more accurately, slaughter) the Canaanites, and settle into the land. After this, comes the prophetic books: the Major Prophets (Isaiah, Jeremiah, and Ezekiel), and the Twelve Minor Prophets (Hosea, Joel, Amos, Obadiah, Jonah, Micha, Nahum, Habbakuk, Zephaniah, Haggai, Zechariah, and Malachi.) It should be noted that "Minor" doesn't mean less important, but is rather an allusion to the fact that those books are significantly shorter than the others. ^_^ The authors of these books are, as far as I know, unknown.
Finally comes the Kethuvim, or Writings. These could be thought of as the miscellaneous writings(though no less important.) These are the Psalms(songs of worship), Proverbs, Job, Song of Songs, Ruth, Lamentations, Ecclesiastes, Esther, Daniel, Ezra-Nehemiah(technically one book), and Chronicles(two books.) With some exceptions, most of these books' authorships are anonymous, as far as I know. (As Jayhawker Soule may shortly remind us, I know very little on the subject.
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Now, let's move on to the New Testament.
The first books are the four gospels. (Matthew, Mark, Luke, and John.) The first three are called the Synoptic Gospels, because of their striking similarities in style, narration, and content. The gospel of John is almost on a plane of its own. Despite the names given to the titles, we do not know who actually wrote them. The names were added by early church leaders as a way of establishing the authority of the writings.
Next comes documents whose authorship we know all too well, as he proudly proclaims his name in the introductions of almost every single one of his letters: Paul.
These run from his epistle to the Romans to his letter to Philemon. With the exception of Hebrews, whose authorship is suspected to be Paul, but is not clear, are letters whose authorships are attributed to the name given to the letter.
The New Testament ends with Revelations, a book written by a man named John. It should be noted that the name John was a common name at the time, so it is likely that this John is completely different than all the other Johns we've thus far come across. (The writing is completely different than the gospel and letters which bear the name.)
