two color led 'blink' sketch- low power on one color

Just trying something out...
I connected a two color led to an attiny13 and programmed it with my arduino.
When I run it one color is very week,...
The code I used is below.
Why is the power for one color/pin so low : And how to solve it

/*
  Blink
  Turns on an LED on for one second, then off for one second, repeatedly.

  Most Arduinos have an on-board LED you can control. On the UNO, MEGA and ZERO 
  it is attached to digital pin 13, on MKR1000 on pin 6. LED_BUILTIN takes care 
  of use the correct LED pin whatever is the board used.
  If you want to know what pin the on-board LED is connected to on your Arduino model, check
  the Technical Specs of your board  at https://www.arduino.cc/en/Main/Products
  
  This example code is in the public domain.

  modified 8 May 2014
  by Scott Fitzgerald
  
  modified 2 Sep 2016
  by Arturo Guadalupi
*/

int LED_BUILTIN = 4;
// the setup function runs once when you press reset or power the board
void setup() {
  // initialize digital pin LED_BUILTIN as an output.
  pinMode(LED_BUILTIN, OUTPUT);
}

// the loop function runs over and over again forever
void loop() {
  LED_BUILTIN = LED_BUILTIN 0;
    digitalWrite(LED_BUILTIN, HIGH);   // turn the LED on (HIGH is the voltage level)
  delay(100);                       // wait for a second
  digitalWrite(LED_BUILTIN, LOW);    // turn the LED off by making the voltage LOW
  delay(100);                       // wait for a second

  LED_BUILTIN = LED_BUILTIN 4;
    digitalWrite(LED_BUILTIN, HIGH);   // turn the LED on (HIGH is the voltage level)
  delay(100);                       // wait for a second
  digitalWrite(LED_BUILTIN, LOW);    // turn the LED off by making the voltage LOW
  delay(100);                       // wait for a second
}

What are these 2 lines supposed to do?

LED_BUILTIN = LED_BUILTIN 0;
LED_BUILTIN = LED_BUILTIN 4;

How is the LED connected?

As this only runs once, only one pin is set as an OUTPUT:
pinMode(LED_BUILTIN, OUTPUT);

Sorry this must be
LED_BUILTIN = 0;
LED_BUILTIN = 4;

This changes the output pin

The led has three legs, the + go to pin 0 and 4

This not runs once, but in a loop. changing from pin 0 to pin 4 (red to green)

attiny13 has not on-board LED...
do not use LED_BUILTIN...

I also tried led = 0; but thats also not working ;(

void setup() {
  // initialize digital pin LED_BUILTIN as an output.
  pinMode(LED_BUILTIN, OUTPUT);
}

You need a pinMode for the 2nd pin you want to use.
setup() only runs once, after a reset; if you only use pinMode once, only 1 pin gets set up as an output.

Try this one.

int ledPin_Culor_A = 0;
int ledPin_Culor_B = 4;

void setup() {
  
  pinMode(ledPin_Culor_A, OUTPUT);
  pinMode(ledPin_Culor_B, OUTPUT);
}


void loop() {
    digitalWrite(ledPin_Culor_A, HIGH);   
  delay(100);                       
  digitalWrite(ledPin_Culor_A, LOW);   
  delay(100);                      


    digitalWrite(ledPin_Culor_B, HIGH);   
  delay(100);                      
  digitalWrite(ledPin_Culor_B, LOW);    
  delay(100);                      
}

Thanks everybody, I understand now what went wrong!