um. you need to cut the old dustcap off, and set some shims to center the coil. then you take a razor and clear off all the old CA glue from the surround landing (foam thing) and the edge of the cone.
then you use CA glue and accelerator to adhere the new surround to the cone. but you gotta make sure its centered or you are screwed. then you ca glue a new dustcap over the hole you cut for the shims.
its dificult.