As you found from the title this is a tutorial, for the JVS light switch, to turn a light on and off.
Step 1. Create your light/lamp, and name the part that you want lit, something like "light".
Step 2. Place a light switch.
Step 3. Wrench the light switch, and open the "Events" menu.
Step 4. From the "Events" menu, put the following into the script menu's;
onActivate > <NAMED BRICK> > setLight > (whatever light you want)
light
onContentStop> <NAMED BRICK> > setLight > NONE
light
There you have it!