how to refit windscreen on ldv 400 convoy 2003 pick-up?

It is difficult to know what is going wrong,have seen these done by windscreen replacement co`s and they make it look easy,working equally along the bottom,up the sides and finishing along the top,are you using some lubricant to help?maybe a small amount of soapy water,also I take it the centre bead is removed while doing this.

cdc
July 2013