Swiping to the left on a line within a list adds bullets and style formatting to set the priority for an item. Swiping to the right crosses it off as done, while swiping down to refresh will clear crossed off items.
From the home screen of the app, you can touch the alarm clock icon in the lower right to view and manage reminders. On this screen you will see items marked with an alarm; you can then open and edit the alarm if you need more (or less) time. You can also mark an item as complete by tapping on the small circle next to the item's name.