arduino

// Define Pins
#define BLUE 3
#define GREEN 5
#define RED 6

void setup()
{
pinMode(RED, OUTPUT);
pinMode(GREEN, OUTPUT);
pinMode(BLUE, OUTPUT);
digitalWrite(RED, HIGH);
digitalWrite(GREEN, LOW);
digitalWrite(BLUE, LOW);
}

// define variables
int redValue;
int greenValue;
int blueValue;

// main loop
//void loop()

#define delayTime 10 // fading time between colors

//redValue = 255; // choose a value between 1 and 255 to change the color.
//greenValue = 0;
//blueValue = 0;

// this is unnecessary as we've either turned on RED in SETUP
// or in the previous loop ... regardless, this turns RED off
// analogWrite(RED, 0);
// delay(1000);

//for(int i = 0; i < 255; i += 1) // fades out red bring green full when i=255

//redValue -= 1;
//greenValue += 1;
// The following was reversed, counting in the wrong directions
// analogWrite(RED, 255 - redValue);
// analogWrite(GREEN, 255 - greenValue);
//analogWrite(RED, redValue);
//analogWrite(GREEN, greenValue);
//delay(delayTime);

//redValue = 0;
//greenValue = 255;
//blueValue = 0;

//for(int i = 0; i < 255; i += 1) // fades out green bring blue full when i=255

//greenValue -= 1;
//blueValue += 1;
// The following was reversed, counting in the wrong directions
// analogWrite(GREEN, 255 - greenValue);
// analogWrite(BLUE, 255 - blueValue);
//analogWrite(GREEN, greenValue);
//analogWrite(BLUE, blueValue);
//delay(delayTime);

//redValue = 0;
//greenValue = 0;
//blueValue = 255;

//for(int i = 0; i < 255; i += 1) // fades out blue bring red full when i=255

// The following code has been rearranged to match the other two similar sections
//blueValue -= 1;
//redValue += 1;
// The following was reversed, counting in the wrong directions
// analogWrite(BLUE, 255 - blueValue);
// analogWrite(RED, 255 - redValue);
//analogWrite(BLUE, blueValue);
//analogWrite(RED, redValue);
//delay(delayTime);
//void setup();
//pinMode(RED,OUTPUT);
//pinMode(GREEN,OUTPUT);
//pinMode(BLUE,OUTPUT);
//digitalWrite(RED,HIGH);
//digitalWrite(GREEN,LOW);
//digitalWrite(BLUE,LOW);
//void loop()
//redValue=255;//choose a vaulue between 1 and 255 to change the colour.
//greenValue-0;
//blueValue=0;
#define delayTime10//fading time between colours
//delay(delaytime);

when i try to upload my code it says this:

undefined reference to `loop'
collect2: error: ld returned 1 exit status
exit status 1
Error compiling for board Arduino/Genuino Uno.

Im quite confused and unsure of what I should do now.

Your sketch does not have a loop() function, because you have commented that out.

Why all the /////////////////////////////// ?

basicengineer:
Im quite confused and unsure of what I should do now.

Start with some of the simple examples in the IDE and learn the correct structure of an Arduino sketch?

You must have a loop() function present - after calling setup() once, it calls loop() repeatedly, so there must be a loop function to call. If you don't need loop() to do anything, you don't need to do anything there - it can just be an empty function.

void loop() {}

But it must be there.