How to make magnetic power?

Answer 1

A note about terminology - magnetic energy is the energy stored in a magnetic field. I have never heard of magnetic power.

However, I assume you are asking how to get electrical power from magnetic phenomena. The way this works is directly from maxwell's equations. Faraday's law says that the rate of change of flux through a loop (field through loop times area of loop) is proportional to the electric field around that loop, which is proportional to the current, if the loop is a conductor.

The generator works by spinning a permanent magnet near a loop of wire. As the magnet spins, it induces current in the loop of wire, which can then be made to do useful work.

A note about energy conservation: when the current in the loop is induced, it is always in such a way as to attract the spinning magnet, so the external agent has to do work to resist this.