Every screen's top bar has a bell icon on the right — tap it to see your notification history for the band you're currently viewing.
A small dot appears on the bell whenever you have at least one unread notification — it's a "something's waiting" signal, not an exact count. It clears the moment you actually open a notification, not just from glancing at the list.
Tapping a notification takes you straight to whatever it's about — an event, a task, or the Music tab for a new piece of sheet music — and marks it as read on the way. Notifications you've already read stay in the list (nothing is deleted), just without the highlight.
Want fewer of these, or none at all for certain kinds of updates? See Changing your notification settings.