planning to make automatic door LM35

hi all
i am planning to make automatic door using an LM35. what i want is when the pin 7 goes high i want it to stay high for 2 seconds just enough time to open the door then stop. then wait for pin 7 to go low for 2 seconds then off until pin 7 goes high again
could any one help
thus opperating a door to open when temp high
close when cold
i could use a relay or mosfet to drive the motor
i have a copy of this sketch

    #include <LiquidCrystal.h>
    int reading = 0;
    int sensorPin = A0;
    int relay =7;
    // initialize the library with the numbers of the interface pins
    LiquidCrystal lcd(12, 11, 5, 4, 3, 2);
    void setup() {
    // set up the LCD's number of columns and rows:
    lcd.begin(16, 2);
    void loop() {
    reading = analogRead(sensorPin);
    int celsius = reading/2;
    lcd.setCursor(0, 0);
    lcd.print("Temperature: ");	
    lcd.print(celsius, DEC);
    if (celsius >35) {
    } else {


Look at how millis() is used to manage timing in several things at a time.

Basically you need to record millis() when the door opens and then keep comparing the saved value with the current value of millis() until 2000 millisec (or whatever) has elapsed. Then close the door.