Wreckage cards are special Event cards. One is put in play when setting up the game: either Food Crates (in a standard game), or a random card if you prefer.
You can gain an early advantage by either assigning one Action pawn and taking the smaller amount of resources, or assigning two Action pawns and taking the larger amount. You must decide on one of these options when placing pawn(s) onto the card; you cannot do both. This counts as a Threat Action.
The Threat Effect of a Wreckage card does nothing.