remove your old cold air return - careful Bob!
attached metal frame to opening - notice it's been partially painted to match the wall.
insert your air filter. Don't forget to change if once in a while for optimum efficiency.
Snap your painted Olympia grille into place. Don't forget to let the paint dry out thoroughly before installing. You will want to be able to easily get it out to change that air filter.
Straighten grille if crooked - easy does it Bob!
final result: perfection!