How do I create store specific tasks?

Navigate to the store you want to add a task to by clicking on the "Stores" navigation on the left menu then select the store of interest.

After selecting the store, press on the "Tasks" link.

Once on this screen you can view the System Wide Tasks and the Store Specific Tasks:

Click on the "Add Task" button to create the task. See Here for more Task Creation Info.

If you are an admin, you can either hit the "Save" button to save to just this store, or you can click "Save to Multiple Stores".  This will allow you to select a subset of stores that you want the tasks to be applied to.