With Smart Notebooks you can simply create a Notebook for all tasks that are marked as Follow-Up:
1) Press the Notebook Icon on the bottom right
2) Press + New Notebook
3) Type the name of the Notebook, i.e. Follow up Tasks
4) Press the Smart Notebook checkbox
5) At the bottom of the list of selections, tap "and their status is" and select "has Follow up"
6) Press Done
7) Press Save or swipe up to Save
This Notebook shows all tasks that have a Follow up status.
Smart Notebooks are very powerful - they effectively give you the power to filter and sort your tasks in so many possible ways. Have fun!