window si;icone from an auto shop its quite easy providing you have decent window rubber i cant remember what my ke seal is like as i havent done one for years but i worked in a panel shop for ages .
basically pull out old window with a razor slice of most of the old silicone leaving a small amount if you can as it helps the new stuff bond better always go base of window in first , and if it has to be partially roped in from memory i think they do ?
then wrap your rope around the window a knot in one end and an old silicone nozzle attached to the other start by inserting the bottom of the window and work your way around . also slap the glass in a downward motion your bare hand will grip the glass and it will help it settle into position .
follow the rubber around untill you get to the top following the slapping technique alll the way around . take your time and use liberal amounts of silicone .
for one of two reasons . mostly so you dont get leaks .
secondly if you use enough you can fill the gap between rubber and and metal preventing any water getting in and rusting away your sil .
good luck its not that hard i suggest you give it a go
oh and clean your glass and excess silicone asap