Place a small ladder in front of the fireplace if necessary to reach above it.
Hold the picture frame against the wall, centering with the width of the fireplace and the length between the mantel and the ceiling.
Mark the location where you'll fasten the retaining hook to the wall above the fireplace with a pencil.
Select a drill bit of the same size as the screw you'll use to fasten the hook to the wall. Fit the bit into the drill and close the chuck.
Drill into the wall through the pencil mark, then back the drill out and insert a plastic anchor. Push the plastic anchor in by hand. If it will not go in flush with the wall, tap it with a rubber mallet.
Fasten the hook to the wall using a screw and screwdriver, then hang the picture frame on the hook. Step back and look to ensure the picture frame is not crooked; straighten as necessary.