Hi,
its not too bad to do.
Step 1:
Loosen the seal: Using your fingers or carefully with a screw driver lift the seal up on the inside of the car to make sure its free and loose.
Step 2:
Carefully start to prise the seal down while pressing the window out. I seem to think it was easiest to start at the top.
Step 3:
Catch the window before it falls out on the floor and breaks !
Anyone else got a better description ?