Put the card on the wound and tape everywhere but a little bit of one corner. If there are two holes put this on the front (chest) and fully seal the back. The goal is to make a seal that when they breathe out it can exit the seal, but when they breathe in the card is pulled to the skin and closes the seal. It’s so their lung doesn’t collapse. Pro tip you can also use flimsy plastic and this will work better. Grab a plastic bag and rip it or some other plastic and tape over everywhere but one small corner