This is one of the harder steps to accomplish I felt. You need to de-solder the four points by heating them up at the same time if possible. They actually have small holes in the center of them for the solder to go through to the bottom pads. Once it is removed you need to clean them off and remove as much old solder as possible without damaging the ribbon they are on. Once you have the new screen in place you need to put the part in its appropriate place and then solder the points. Using an ample amount of flux is helpful but you have to clean up afterwards with IP alcohol. If you have a small microscope or good camera you can zoom in and see if the connections are solid and then you are done.