Flip it depending on if you want the hanger hole on the top, sides or bottom.
drill a hole the back side and thread in a set screw, place on the corner of your foam core board and use the set screw to secure the board. Hang from the printed mounting holes using wood screws, nails, zippy ties, string, or whatever you have.

If you use screws, you can drill out the front hole larger so the screw head is recessed

Drill hole on the side you want to be the back and thread in a set screw