headlights not working

Ok, so with the ohm meter hooked up do I turn the vehicle to the on position? Or just turn on the headlight switch? What is supplying power while I'm looking for the resistance?
I'm assuming there should be a resistance measurement when this is hooked up like this when I wiggle the bulkhead connection.
Just a little confused, if there is supposed to be zero resistance just sitting like this what does wiggling the bulkhead actually do to supply a measurement?
I'm not electrically inclined as you can tell.