A switch is on or off. An LED has a maximum allowed current that must never be exceeded.
Your circuit has switched 9V from the switch blowing up the LED because you have nothing in series to limit the current.
If you want to use the switched 9V to power something else then use it since the LED and its current-limiting resistor have nothing to do with the voltage.
Thick = not intelligent. I think he may mean a momentary confusion probably common to beginners when we are overwhelmed where an issue with the circuit bamboozles the brain into not seeing something obvious or getting your knickers in a twist with a problem then seeing it. I never have such moments on a frequent basis, I just know some-one who does, honestly.