Click the extension icon. This will open a new tab with example pdf. There you can experiment with the extension or open any pdf on your computer. To start taking notes go to View -> Sidebar -> Pdf With Notes.
Now you have your pdf open and the sidebar to write your notes. Focus the input field in the sidebar and while reading/scrolling the pdf you are learning start typing a note and hit enter. This will save both your note and the position you were in the book when you started typing it. After you have gather a good amount of notes you can start explaining what you've read with the help of all the notes you made. The notes shouldn't be long but rather act as a reminder what to talk about. If you can explain well a note you can check it's checkbox. If you cannot explain a note well just click it and it will show exact place in the pdf you wrote it so that you can go over again what you couldn't understand so next time you can explain it and once again mark the checkbox. While the input is in focus Ctrl+e exports your notes to a file and ctrl+shift+z will let you import your notes.
