Where did they get the information for the old testament to write it?

God reveals Himself to us also.  Faith brings us alive and makes us holy.  You are as much a prophet as Amos or Obadiah.

So, start writing!

Must of the writers were there, except for Genesis. 

Much was plagiarized,  such as the Noachian flood. This story was first told by the Sumerians, rainbows and all.

Hi Donna,

The writers/storytellers of the Old Testament were inspired by G-d to write what they wrote. 

They were also influenced by stories that were told to them in their homes and villages, which their elders had preserved through the oral traditions. 

All of us have this capacity to write down and to tell our stories and our beliefs, that is why stories evolve and grow more detailed, but if the words/thoughts are inspired by G-d's Indwelling Spirit, which is Holy, then the stories will be Holy as well. 

Plagarism will happen when the story is believable and excellent.  No one ever wants to steal an idea or thought that is false.  The early writers of the Bible were attentive to their world and they listened to that "still, small voice" within, which we also have today. 
The difference is:  Many of us do not want to listen to that voice, because it interfers with our own. 

2 Timothy 3:16, 17 -All Scripture is inspired of God... also 2 Peter 1:20, 20 indicates that man was inspired by holy spirit to pen the prophecies of the Bible. The information contained in the Bible was penned over a period of 1,600 years and the writers lived at different times, coming from many walks of life. Genesis tells us how man's problems began and Revelation shows that the whole earth will become a paradise (garden) as it was intended. The harmony of the Bible proves that is came from God and not from man's imagination or thought process; the entire Bible relates in some way to the unfolding of God's purpose which is what we can expect from Almighty God!

The Bible is based on facts and it is inspired by God.