Some of the writers wrote down exactly what God said:

Take thee a roll of a book, and write therein all the words that I have spoken
unto thee against Israel . . . (Jeremiah 36:2)

Other writers wrote what they experienced or what God revealed concerning the future:

Write the things which thou hast seen, and the things which are, and the things
which shall be hereafter. (Revelation 1:19)

All of the writers wrote under God's inspiration the words of His message for us.