Its a simple arduino controlling a RGB LED. Nothing fancy here:

Both the blink frequency and brightness of LEDs can be controlled simultaneously by the rotary potentiometer. The more the LEDs are brightened, the faster they blink.

My last homework is to use one pushbutton to control one RGB led’s color and two led light . When you push , the rgb  will become green and other green led light up . Then you push again , rgb becomes red and the green led  light fade , the red one light .