Within your clan, tap the STAGE button where you will see your current season and stage.
   

The currently active stage will be highlighted and contains the available Clan Games for you to participate in. Tap the “i” button to see a Clan Games' goal and how you will complete it in the game.

 

Start spinning to achieve the clan goal as many times possible as long as the game is active. If you forget what the goal is, you can always click on the Clan icon to see it!