Measure the outside dimensions of your map. This will determine the dimensions of the frame you will need to purchase.
Place your frame on a flat, clean work surface with its back facing you. Lay the glass on top of the lip inside the frame that will hold it in place. Spritz the glass with window cleaner and wipe it dry with paper towels. Flip the glass over so the opposite side is facing up. Wipe the surface clean with cleaner and paper towels.
Lay your map face down on the glass. It should fit inside the frame with no edges visible from the front of the frame.
Cut your foam core to the same dimensions as the map, using a box cutter. Lay the board over the back side of the map. The foam core is sturdy and will protect the back of your image.
Attach the hardware to the frame, according to the manufacturer's instructions. Your frame will include fasteners to secure the back and wire for hanging the frame.