First strip all of the handles, winders, levers, etc off of the inide of the door. Most of these bits are screwed into place, and prety obvious how to undo. The exception can be the window winder (asuming it's a manuel window, not electric). This is held in by a larg spring clip, under the thin plastic 'washer' around the base of the winder. A couple of small screwdrivers, and a little patients will get this off.
Then remove the door card. Be carfull when un-poping the fixings, as you could tear the card. There should be a plastic sheet under the door card, stuck into place. Peel this away.
slid the winder back on without the clip. Move the wind mekanism up / down so you can get at the bolts holding the old window bottom (metal strip that grips the bottom of the glass). Undo these and remove old melat strip.
at the 'rear of the door find the gide rail that the glass slids through when in opperation. This unbolts at the bottom, and slides out. Remove it.
Slide the new glass down into the top of the door (through the slot it normally comes out off when closing) nose down. You may need to remove the plastic strip along the side of the opening to allow this. As the glass goes down into the door, twist it round to the correct orientation.
Bolt the strip of metel at the bottom of the glass to the winding mecanism.
put everything back together in reverse order to how it came apart. Don't forget the gid rail from the rear of the door. the window will need to be up to do this.
When you come to put the window winder back on (if it's manuel) clip the spring clip into place first, then just push the winder onto it's splines. The clip will click into place once it's in the right place.