Problem using RGB LED

ok bros, im tryna power up an RGB led and now im coding it and its IMPOSSIBLE! Please help me

error code: Arduino: 1.8.13 (Windows 7), Board: "Arduino Mega or Mega 2560, ATmega2560 (Mega 2560)"

C:\Users\LUIXIU~1\AppData\Local\Temp\ccWOdEZf.ltrans0.ltrans.o: In function `main':

C:\Program Files (x86)\Arduino\hardware\arduino\avr\cores\arduino/main.cpp:43: undefined reference to `setup'

C:\Program Files (x86)\Arduino\hardware\arduino\avr\cores\arduino/main.cpp:46: undefined reference to `loop'

collect2.exe: error: ld returned 1 exit status

exit status 1

Error compiling for board Arduino Mega or Mega 2560.

This report would have more information with "Show verbose output during compilation" option enabled in File -> Preferences.

i got a elegoo board Arduino Mega 2560 Starter Kit

This is the code:

// Define Pins

define BLUE 3

define GREEN 5

define RED 6

: undefined reference to `loop’

Oops

Well if this is the whole code :

#define BLUE 3
#define GREEN 5
#define RED 6

then obviously something is missing.