This article explains how to use Web Notes in Microsoft Edge versions before the April 2020 Update.
Using Web Notes on Microsoft Edge
The Microsoft Edge web browser is secure, easy to update, and works well with other products in the Microsoft ecosystem. A popular feature of Edge is Web Notes. Use Web Notes to scribble notes on a web page, just as you would write your thoughts on a journal or essay.
To use Web Notes, open the Edge browser and navigate to the web page you want to annotate.
Select the Take Web Note icon in the upper-right corner of the screen. (It looks like a broken square with a pen in the middle, or a pen scribbling a wavy line.)