If you want to see all your Group Notes and Private Notes in one place, first tap the Group Details icon, which is second from the left at the bottom of the screen.
This will take you to a list of your fellow Members. Tap Notes on the far right.
You'll see two tabs, one for Group Notes and Private Notes. Tap whichever notes you'd like to view, and then tap the Week you'd like to view.
Please note this is only for viewing, not editing. Here's how to add Private Notes, and here's how to view the Group Notes for the week.