two arduinos communicating together??

[system]

anthony8i:
thanks! Yeah I do get the concept but I really need an example?

Here is the button example:

// constants won't change. They're used here to 
// set pin numbers:
const int buttonPin = 2;     // the number of the pushbutton pin
const int ledPin =  13;      // the number of the LED pin

// variables will change:
int buttonState = 0;         // variable for reading the pushbutton status

void setup() {
  // initialize the LED pin as an output:
  pinMode(ledPin, 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) {     
    // turn LED on:    
    digitalWrite(ledPin, HIGH);  
  } 
  else {
    // turn LED off:
    digitalWrite(ledPin, LOW); 
  }
}

Now add some sending:

const int buttonPin = 2;     // the number of the pushbutton pin

// variables will change:
int buttonState = 0;         // variable for reading the pushbutton status

void setup() {
  // initialize the pushbutton pin as an input:
  pinMode(buttonPin, INPUT);     
  
  // initialize serial
  Serial.begin (9600);
}

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

  // send to other Arduino
  Serial.print (buttonState);  
  
  // give it a chance to react
  delay (100);
}

Confirm in the serial monitor that you see 0 or 1 being sent.

Now look at one of the serial examples to read in the 0 or 1 and light up the LED on the other board appropriately.

hey thanks I will upload this to my aduino; but do up load this to both arduinos? and to send the data I just connect the TX to RX right?