1.Remove the screw on top of the lamp assembly. The lamp assemble come off as one unit. There are three contact clips that hold the lamp on. They may be frozen fast. You could spray oil to loosen before removing lamp assembly.
2. In order to remove the lamp,you have to push down on the top of the lamp(this loosens the top pin from the holder, try to pull the assembly straight out.) If the light assembly has been in for a few years,you'll have to do some tugging and pulling with it. The clips may snap off and need to be replaced before putting in a new lamp assembly.
you could also try to look here on car repair guide
,they have some how to videos there that may help you.