Welcome to the community!
I guessing you are going to want to use a prompt to be able to edit the notes field. You can accomplish this by using [?Note;;;;]
in the notes field of the action. “Note” can be any text you want to appear before the edit text field of the popup.
Here is a link to better explain the prompt notation:
You should be able to view the note you typed in thru Manage->Entities->Entities-> in the notes tab.
You may have to use a Load Entity action before the Update Entity Note action.
If that does not work, post some screen shots of your action(s) and rule(s).