You will need a transformer. If you can get a universal transformer (one with a voltage selection switch) then you can start at 3v and keep moving up until you feel the resistor get warm (don't worry, you're gonna feel it through the heatshrink) or the LED pops. then you know it's too much.
The resistors I would have to guess are designed for 14v so a 12v transformer would *Probably* be correct, tho 9v would be safer, you would just need more LEDs
Also keep in mind LEDs are polarity sensitive, so if you hook one up and get no light, try reversing the power wires.
DO NOT hook an LED up to AC Voltage, and never directly to a 120v outlet. you will exceed the forward and reverse limits and at best burn your hand, at worst you will send plastic shrapnel flying everywhere.