Carefully place the mesh into the pre drilled holes, start at one end and work around. Whenever an area is seated nicely, bend the wires over on the inside. Continue around until the grille is seated properly and all the wires are bent over. Take care to ensure that the wires are bent sufficiently that they cannot come out later.
Caution!!! Use protective gloves and a metal tool as needed to bend the wires over!!! One unprotected slip of the hand could bece an emergency room visit!!