Lighting - SpotLights
    Spotlights are used to do the finishing touches on your map, and make it look more
    realistic. The good thing is that they are fairly easy to add to your level.
    All you need to do is give the light source a target, and it projects the light
    towards that target, and nowhere else...here's how its done:
    Select your light source and press 'N' to bring up the Entities window and add a
    Key called target and a Value called spot1
                       

    Now create an entity called info/info_null and position it where you want the light
    to project to from the light source. Select info_null, and bring up the Entities window
    and add the key targetname with the value spot1 .
                       

    This links the entities together so that the light source projects towards the entity
    "info_null" . Now compile the map and check out your spotlight!
           
         

                       
             
No spotlight
           
         

                       
               
Spotlight