I have created a device to fade LED in a sequence with schematic, circuit, codes, a button, for loops, digitalWrite(), digitalRead(), and analogWrite(). I built it with Arduino and implemented it on a breadboard.

1. I have first calculated the appropriate resistance for each LEDs. The red, yellow, and green have a same voltage drop. I calculated them at the same time.

2. Then with the value of resistor, I have drew the schematic for the circuit.

According to the schematic, I have built the circuit with Arduino on the breadboard.

          
            // constants won't change. They're used here to set pin numbers:
            const int buttonPin = 2;  // the number of the pushbutton pin
            const int ledPins[] = {9, 10, 11};    // the number of the LED pins
            // variables will change:
            int buttonState = 0;  // variable for reading the pushbutton status

            void setup() {
              // loop through the ledPins array:
              for (int i = 0; i < 3; i++) {
                // initialize the LED pins as an output:
                pinMode(ledPins[i], OUTPUT);
              }
              // initialize the pushbutton pin as an input:
              pinMode(buttonPin, INPUT);
            }

            void loop() {
              // read the state of the pushbutton value:
              buttonState = digitalRead(buttonPin);

              // check if the pushbutton is pressed. If it is, the buttonState is HIGH:
              if (buttonState == HIGH) {
                // loop through the ledPins array to fade in each led:
                for (int i = 0; i < 3; i++) {
                  // fade in from min to max in increments of 51 points:
                  for (int fadeValue = 0; fadeValue <= 255; fadeValue += 51) {
                        // sets the value (range from 0 to 255):
                        analogWrite(ledPins[i], fadeValue);
                        // wait for 10 milliseconds to see the dimming effect
                        delay(10);
                      }
                }
                // loop through the ledPins array to fade out each led:
                for (int i = 0; i < 3; i++) {
                  // fade out from max to min in increments of 51 points:
                  for (int fadeValue = 255; fadeValue >= 0; fadeValue -= 51) {
                        // sets the value (range from 0 to 255):
                        analogWrite(ledPins[i], fadeValue);
                        // wait for 10 milliseconds to see the dimming effect
                        delay(10);
                      }
                }
              } else {
                // loop through ledPins array to turn LED off:
                for (int i = 0; i < 3; i++) {
                  // turn LED off:
                  digitalWrite(ledPins[i], LOW);
                }
              }
            }