Update data in DB

I can see your function edit()
But not that this function is ever called.
In you controller when the form is valid you need to call the edit function to save the data.

You also always call $this->tutoriel_model->ajouter_tutoriel() that will create a new record every time.
it will not update any existing data.

On the package it said needs Windows 7 or better. So I installed Linux.