First, sketch you ideas for your design - think about the shape of your medal - you may want to keep it as a circle, or you may want to change it's shape.
Then think about the colours for the medal ribbon - you may want to stay with the colours as shown above.
Collect the materials that you will use to make your medal - you will probably use cardboard, paper, maybe silver foil?
Then make your medal.
Finally, you could take a picture of your medal and send it to school via email - or you could even take a picture of you wearing your medal - you could even give a salute in your picture!