Ah, hanging Christmas lights inside windows can be a bit tricky, but it's definitely doable! First, make sure the lights are LED lights, as they are safer and more energy-efficient. Then, make sure you have the right type of hooks or clips to attach the lights to the windows. Use a ladder or a stool to reach the top of the window, and be careful not to break any glass. Finally, make sure the lights are evenly spaced and that you have enough power outlets to plug them all in!