How do I add a card to a deck?
Press the Add button under any card in your library.
After pressing that button, a window will open that will let you add another copy of that card to your library or add that card to a specific deck.
You can use that same window to remove a card from your library or deck as well.
If you already have a card in a deck, you can add a card with the Plus or Minus button under a card while viewing the cards in your deck.