Which books of the bible are you suggesting are unimportant (since, as you say, Jesus didn’t tell anyone to write them down)?
But, of course, He did tell all those that recorded the books that make up the scriptures to indeed write them down—by His Spirit.
You said,
‘Don’t you think if it was that important He would have told us to follow the book that would be written?”
Yes. He said at one point to the Jews, “Search the Scriptures; for in them ye think ye have eternal life: and they are they which testify of me.” And, of course later He said, “Follow Me.” (emphasis on the “Me”)
Thus proving you have to go outside of Scripture for direction and simultaniously disproving sola scriptura.