Where is the energy input to produce light in your home?

Assuming you mean electric lights, then eventually the power company. The power company generates power, and sends it over power lines to your home. These are the same power lines that you might see crossing the interstate, or traveling parallel to the city streets. If no power line visibly connects to your home, you might have an underground power line. They're generally much more expensive, but less susceptible to the weather, and much more sightly.