Put goop on the under side of it. If you've never done a surround swap its kinda a pain in the azz. If your deadset on just replacing the surround I got some nylon impregnated surrounds that I stock loose at the shop.
is it easier/cheaper to do that? i have never done any kind of speaker work. i just thought you cut off the old surround, clean the sub and basket then glue the new surround on.