Don't you have to know the Vf to size the resistor? Regardless, that doesn't make a lot of sense to me? Where would I put the probes to find the forward voltage? On each side of the LED? Or would I take a measurement of the voltage from V+ to ground, before I added the LED and resistor, then after I add the LED and resistor, then subtract after from before? As for the resistor, I assume I would just use the typical Vf for that LED to size it?
Thanks again for answering all my newbie questions. I just want to make sure I have a good understanding before I start building anything.