GNotes is not available for Windows but there are plenty of alternatives that runs on Windows with similar functionality. The best Windows alternative is Joplin, which is both free and Open Source. If that doesn't suit you, our users have ranked more than 100 alternatives to GNotes and loads of them are available for Windows so hopefully you can find a suitable replacement. Other interesting Windows alternatives to GNotes are Standard Notes (Freemium, Open Source), Google Keep (Free), Microsoft OneNote (Freemium) and Evernote (Freemium).
Joplin is a free, open source note taking and to-do application, which can handle a large number of notes organised into notebooks. The notes are searchable, can be copied, tagged and modified either from the applications directly or from your own text editor.