I am aware of plastic trim on these windows but no glass trim. If you are talking about the black plastic trim piece it has a channel inside of which fits a rubber channel. Take the rubber channel an fit it on the glass. Then take the plastic channel and fit it over the rubber channel which is now on the the glass.
Using a rubber mallet and a bloc of wood tap the plastic channel piece into place until tight. This is a friction fit. Don't use much force and tap up and down the length of the plastic trim.
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