Communication between two arduinos

I'm wanting to set-up two arduinos to send binary data between them Using Using the TX and RX Pins.

I was wondering how I would go about doing this?

Thanks for any advice B.

Try this, send 1 to 10, blink on board if it is received.

void setup(){
  pinMode (13, OUTPUT);
  Serial.begin(9600);
}
void loop(){
  for (byte x = 1; x<11; x=x+1){
    Serial.write(x);
    delay(2000); // dumb delay to give receiver a chance to count LED flashes
  }
  if (Serial.available() >0){
    byte blinkQty = Serial.read();
    // flash on board LED from 1 to 10 times
    for (byte x = 0; x <blinkQty; x=x+1){
      digitalWrite (13, HIGH);
      delay (50);
      digitalWrite (13, LOW);
      delay (50);
    }
  }
}

Don’t forget to connect the grounds.
Could even connect Rx to Tx on same board & try it.