First - I assume you're trying to replace the felt channel that the glass tucks into when closed,right? If so -
click here to read the factory procedure. Here's some more tips:
DO NOT remove the outer sealing rail, the long/flat rubber piece at the bottom of the glass, on the outside of the door! Don't touch it. You do not need to remove the window glass, or even loosen the bolt shown in the factory procedure, just roll the window down. Remove the door panel as shown
here. Remove the *inside* sealing rail at the bottom of the window glass, after the door panel is removed (it may come off with the door panel, if not, it pries off easily).
Now pull the old felt channel out of the metal window frame. Make sure you bought the right part... early cars have 3mm window glass, later cars have 4mm, the felt channels are different for each. Lube the back side of the new felt channel with a soapy solution, or spray lubricant, or something similar to help it slide into place. Install the vertical section first, then the top "corner", and work your way down the curved side. The hard part is getting the felt channel all the way down into the guide inside the door. I use a long (3-foot) piece of thin metal bar from Home Depot, about 3/4" wide and 1/16" thick. This slides down the window slot and you can use it to push the channel down to where it goes past the glass. You will need a flashlight to see inside the door. Make sure the felt channel is fully seated and not buckled, or it will jam when you try to raise the window.
When it appears to be fully in place, slowly raise the window a few inches at a time, checking with the flashlight each time, to make sure the felt isn't moving. It should stay in place until the window is fully raised up.
Then re-install the inside sealing strip, and the door panel.
