RGB led connections for arduino
RED_pin to pin 11 on arduino
GREEN_pin to pin 12 on arduino
BLUE_pin to pin 13 on arduino
If you have the led with common anode or negitive terminal, connect it on the 'gnd' on Arduino ('gnd' is the negitive terminal in an Arduino).
If you have the led with the common cathode or postive terminal, connect it to '+5'/'5v' on arduino (it is the positive terminal in an Arduino).