Hi, First of all remove the door panels, side ribs on the doors then un install the old window channels so that the glass is free & easy to be pulled out.
Unscrew the 2 screws of the railing. If they cannot be unscrewed easily then instead of spoiling the screw mouth, its better to heat the screw with a Heat Gun be sure no to point the gun towards the door or else the paint on the outer side will get spoiled.
Pull the glass out then use a flat screw driver to lever the old railing out.
Clean the glass, install the new Rubber & Railing
Apply some good Grease to the grooves
Insert the Glass back & fasten all screw back. Run the window up & down then Install the new window channels.
At the corners, cut a wedge at both sides sothat the channels can be easily lifted up & in proper place when the window glass is Up.
Cross check all things again
then Install the door panels again.