The Short Version: Pick a card from the deck, and do what it says.
The Long Version:
Start by shuffling the deck, or lay out the cards by category or difficulty.
Each player takes turns picking a card from the deck.
Simply follow the prompt on the card. You can choose to skip it, or double down based on your comfort.
Go back and forth between players until satisfied. You can choose to play a few cards or go all night ;)