From the home screen, select Classes, and make sure you use the drop down to pick which class you're working in.
Select Assign Flags
When you go to assign a flag, you have the option to use existing flags that you or your district has created before or you can create a new flag right on the spot.
If you want to create a new flag…
Enter a Title for the Flag
Select a Color for the Flag
Now your new Flag is created and you can use it at any point in the future.
To finish assigning the Flag…
Select the desired Flag (or Flags) from the list
Select the desired student(s)