Like most solitaire games, the main objective is to pick cards from the playing field. In this particular solitaire, you can pick cards that are one higher or one lower than the top card of the deck, regardless of the suit. The deck is shown at the bottom of the screen. A Two is higher than an Ace.

Pick a card either by dragging it onto the faceup card in the deck, or simply by tapping it – if this card can be picked, it will automatically fly onto the deck.
You can only pick cards that are not covered by other cards. If any part of a card is positioned under another card, the lower card cannot be picked.
Some of the covered cards are facedown. A card will turn face up when there are no more cards blocking it, but until then you won’t know what that card is.
If none of the cards on the table can be picked, you can open the next card in the deck by tapping on it.

To pass a level, you need to remove all of the cards from the table. If there are golden cards on a level, you need to remove all of the golden cards (normal cards can remain on the table). The number of cards that you still need to remove is displayed in the upper-left corner.
Remember, the number of cards in the deck is limited, and you will need to pass the level before you run out. The number of cards remaining in the deck is displayed at the bottom of its unopened card.