Move all cards to the 8 foundations from Ace to King. On the tableau you can place cards on other cards in descending order and alternating color. Click on the stack (top left) to get new open cards.
Try to build a house of cards. Make sure the foundations and lower layers are strong enough to support higher layers. Walls are pairs of the same value or suit. Roofs can be any card. Walls of 20 and 21 in value have special capabilities.