Included free with your Medal Hanger are 2 x keyhole spacer blocks and 2 x rectangular blocks. These are designed to be glued to the back of the Medal Hanger. The keyhole spacers can be hooked onto the wall if you put screws or nails in the matching position.
The rectangular blocks can also be optionally used and attached to the wall with Mounting tape (a strong double-sided tape) or 3M Wall strips cut to size, or glued on if possible.
Further help on attaching keyhole style to wall
https://www.wikihow.com/Hang-a-Picture-with-a-Horizontal-Keyhole-Slot
You may also choose to purchase your own mounting hardware.
The basic idea of mounting the Hangers using spacer-blocks is we want the Hanger offset from the wall, so that the Ribbons and Medals can hang freely.
Alternate Hardware
Picture Hanging Screws 
Source: Bunnings
Sawtooth picture hanger
How to Hang Sawtooth Picture Hangers
Suppliers