Connect any GND pin to an empty minus-Rail on your breadboard

I prefer to use pin 39 on my RPi2B to have more structure

Connect your LEDs

1. Red LED with a 220Ω-resistor on Pin15 (use a red m-f-wire), connect to GND-to-minus-Rail
2. Yellow LED with a 220Ω-resistor on Pin13 (use a yellow m-f-wire), connect to GND-to-minus-Rail
3. Green LED with a 220Ω-resistor on Pin11 (use a green m-f-wire), connect to GND-to-minus-Rail

Connect your Button

1. Use a white m-f-wire and connect one side of the button to Pin8 on your Pi
2. Connect the other side with a black m-m-jumper to the GND-to-minus-Rail