To install rear window glass, first remove the old caulking with a knife and ensure that the urethane is completely removed. Next, spread the urethane primer, the new caulking and the urethane on the frame, then place the new window in place.
If your insurance claim covers the cost and you have a few hours on your hands, you should probably go to an auto-window replacement service and get the job done professionally. However, if you do not have the time or insurance coverage, you can do the job yourself. All you need is a DIY window replacement kit, a new rear window and a razor. Use the razor to cut out the old window and remove any weather stripping or urethane that is stuck to the frame. This usually takes a considerable amount of time and requires a lot of patience.
Once the frame is clean, use an adhesive or urethane primer, whichever is available in your kit, and apply it on the frame. Wait for it to dry a little before adjusting the rubber weather strip or urethane, so the adhesive does not smudge. Wait until the adhesive is completely dried before putting the rear window in place, ensuring that the window fits perfectly and is not loose.