HC-SR501 PIR Infrared Motion Sensor

val = digitalRead(inputPin); // read input

So, you have an input connected to the input pin. What the help kind of input?

int pirState = LOW; //

if (pirState == LOW) {

Well, of course it's going to be true.

What is the point of f**king around with pirState? Most people would actually read the state of a PIR sensor.

this is the sketch he/she gives with it

If that is really true, you should send it back, and demand your money back. The seller is too stupid to be allowed to use ebay.