just take it down to a windscreen replacement centre , they will do it for you , there are various methods used, one is the spring clip which you pull out , another is the facia unclips off the winder and reveals a screw, another pulls straight off, another is the surround on the winder, ie the rounded piece that buts up to the door slides forward and it releases off from there ( i think thats the one you have ??), like I say if you are unsure just pop into a windscreen place they won't charge you I am sure ...