Be the first to finish your cards. Play a card that matches the shape or the number on top of the pile. If you cannot play, go to market and pick one.
If the market finishes, the cards that have been played are shuffled back in and the game goes on.
With three or four players it is a knockout. When someone checks up, everyone counts the cards in their hand and the highest count goes out. The rest play again until one winner is left. Stars count double.
Some people play that a 2 can block a 2 and a 5 can block a 5, and then nobody picks. Turn that on in Settings if that is how you play.