CIRC08 is quick to wire up:

1. Longer end of the LED connects to a 560 ohm resistor, which connects to ground.
2. The shorter (cathode) end connects to the metro's digital Pin 13
3. The middle pin of the potentiometer connects to Analog Pin 0
4. Outer pins of the potentiometer connect to the 5V and GND rails. 

Printable Breadboard Sheet