If you put a screwdriver near the front, I may be forced to visit your shores post-haste, to administer a clip over the ear...
Disconnect the negative at the battery. Stick your hand up behind the dash, to where you can feel the box-like shape of your switch. At the bottom of this "lump" is a little spring button, approximately centred.
While pushing this spring button up as hard as you can, pull the switch knob all the way out. It will come clear of the switch. Now, the threaded fastener holding the switch is exposed. Use a special tool, screwdriver, whatever, to unscrew the bezel without marring it. Place the bezel safely while you continue.
The switch needs now to be disconnected from the harness. The harness plug piggybacks onto the switch top. Some are held in with spring clips. If you can feel two 1/4" wide straps - one each side, these are the spring clips. You need to pry them loose with a flat bladed driver. After this, you can pull and wiggle the switch free from the harness plug.
Now it's out, you can see a little better how to reclip the harness to the new switch unit. Proceed in the reverse order, except to reinsert the switch knob/shaft, you only have to push it all the way in.
Hope this helps!
Adam.