LED Resistors and Ohm's Law

[RevengeoftheSeth]

So I've been studying Ohm's law at the suggestion of some of the sticky topics on these forums and I think I have a pretty firm grasp of the concept, now. Basically I=Current in Amps, V=Voltage, and R=Resistance in Ohms.

The formula is R=V/I.

I do have a question on how I figure out what resistor I need for the correct LED.

I will use a blue Lux III for example.

Forward Voltage = 3.9 V
Current = 1 amp
Battery Voltage = 6 V

My question is which voltage do I formulate off of - the battery or the forward voltage of the Lux III? And what do the Watts correlate to on the resistors?

Thanks!

EDIT: RAWR! I figured it out. I scowered the boards some more and found out that V is not just one voltage. Its the difference of the supply voltage and the forward voltage of the LED. That made a lot more sense. Now I just need to find out how many watts I need on the resistor. Can someone throw me a bone on that one?