creating active objects or spots otherwise said HotSpots

As you can see in the development I have attached below, I have areas where users will click on to activate services lik skype, facebook etc I read somewhere about doing just that but I cannot find back where in the doc it is mentioned? Can somebody help me with this? Thanks yves

http://yvesbodson.perso.sfr.fr/hall_stand.html

You would create hotspots by attaching Colliders to the objects you want to be clickable.

Then use the Camera.ScreenPointToRay function to send a ray out where the user clicked and check if it hit one of your colliders.

function Update () {
   if (Input.GetButtonDown ("Fire1")) {
      // Construct a ray from the current mouse coordinates
      var ray = Camera.main.ScreenPointToRay (Input.mousePosition);
      if (Physics.Raycast (ray)) {
          //Check which object was hit and do something
      }
   }
}