To mark your tasks as completed, you can simply click on the circle next to each task or click on the task and mark it as completed.
How to delete a task
If you're noticing any tasks that are irrelevant to your wedding you can easily delete them from your checklist.
To do this, click on the task at hand and click on "Delete task" to get rid of it.
If you want to recover any of the tasks you've previously delete, go to the All tasks tab on your checklist and you'll notice the delete task has been greyed out. To recover it, click on the task and click on "Recover task" and you'll notice it has been re-added to your checklist!