Every Solitaire has 3 stars/ goals to achieve. For example: solve 100% of a Solitaire, solve all cards in a given time, solve a certain number of cards in a row, or reach a certain amount of points.
HINT! In order to get the stars, you have to clear the Solitaire in that game, too. Hence, if you already achieved the goals in a game, make sure to finish off all cards!