The picture on the left is showing the motor coils originally used to generate the magnetic field. We can replace the coils using the neodymium magnets. The magnets have to be placed into the same directions, where the original coils were. This ensures that the magnetic field orientation, necessary for the motor operation, remains the same. In this motor, there are four coils, thus we need to use four magnets. On the right picture you can see the hard drive and the neodymium magnet you can salvage from it for free.