In this tutorial I made, your going to learn how to make a light switch and a light that has an effect and returns from it.
First, your going to need to set up a switch, like my grey block in the wall, and a light on the ceiling like I've done so here:

Next, setup a name for your switch and your light. Your going to want a different name for your light, considering how many you have in your house/building/area. I suggest having a '_#' after the name of your light, so it's easy to know which one your using. If using a house, you could also include the room name and number after the name of the light.

Finally, click send and click your grey switch. Enjoy your lights!

Rate tutorial on x/10 if you wish :D