int pushButton=0; //button´s state
int state=0; //0=led off, 1=led on
int pushButtonPrev=0; // previous button's state

void setup() {
  pinMode(8, INPUT);
  pinMode(5, OUTPUT);
}

void loop() {
  pushButton = digitalRead(8); 
  if ((pushButton == HIGH)&&(pushButtonPrev==LOW)){
    state=1-state;
   }
  pushButtonPrev=pushButton;
  if (state==1){
    digitalWrite(5, HIGH);
  }
  else{
    digitalWrite(5, LOW);
  }
  delay(100);
}