Creating CKEditor Custom Button

I am new in vaadin for using the ckeditor, I need to add a custom
Button
with
custom function/method
to the ckeditor toolbar, What can I do?

Your best bet is to look at how the ‘vaadinsave’ plugin was done in the CKEditor for Vaadin add-on. If your button action is pure JS, you can just add it to your CKEditor plugins directory. If it needs to communicate with the server/Vaadin, you’ll need to modify a copy of the app to deal with the linkage between your button and events triggering on the server.