First, you'll want to wire the PCA9685 breakout to your PI: GND to GND, VCC to 5V, SDA to SDA, and SCL to SCL. Next, wire a second GND pin from the cobbler to one of the ground lines on the side of the breadboard. Next, our LED: the long leg wires to ground. The leg by itself on one side of the long leg is the red channel; wire that to the 0 column PWM row pin on the PCA9685 board. Green and blue are on the other side; wire them to PWM-1 and PWM-2, respectively. Once this is all done, your project should look similar to the following: