Once a regatta starts, your job is to help your co-op by completing tasks. Your personal task journal records all the tasks you've completed or dumped and the number of points you've earned for your co-op in the current regatta (Statistics button).
Tasks marked with a flag icon are special seasonal tasks. Completing them gets you more tokens that you can use to buy unique decorations and rewards.
Most tasks are time limited. You can see how much time you have left to complete your current task and how many points it will earn for your co-op by tapping the task's icon in the Tasks tab or on the main screen (on the right).
Co-op leaders, co-leaders, and elders can dump any task that hasn't been picked in the Tasks tab. It takes 30 minutes for new tasks to appear. Every co-op member can complete a maximum of 7 to 15 tasks depending on the league their co-op is in (the higher the league, the more tasks there are available). If you run out of tasks, you can buy an extra one using Township Cash.
Each task has its own difficulty level, which is why the number of points you get for completing them varies. The higher your league, the better your chances are of getting difficult tasks. The maximum number of points you can get for a task is 135, with relay tasks being the exception—they can earn a co-op up to 145 points. You can read more about relay tasks in the How do relay tasks work? article.