How to navigate between monthes in Vaadin Calendar

Hello..
I'm newbie in Vaadin and i want to implement Vaadin calendar exactly as shown in the sampler: http://demo.vaadin.com/sampler/#ui/data-input/dates/dates-calendar
Unfortunately normal Calendar don't implement monthly navigation like the weekly navigation do.
Please any hint to help to remake the sampler calendar.
Thank you very much

Kim Leppänen: Click on the "i" icon in the right top corner. Choose the "source" tab and you can see the source code for the code example.

That said, there doesn't seem to be the code for the navigation. The calendar's resolution and dates shown are managed through setStartDate and setEndDate. If you want to implement month navigation buttons, create two buttons with ClickListeners. Inside the listeners, change the Calendar's start/end date back/forward according to what the user clicked.

Thank you very much; i thought of that , can you provide a code example of that
 

What did you try yourself? Where did you get stuck? 

Sorry for my absence i've been very busy lately with another projects so i put my Vaadin personal project on stand-by  .
The problem is that i don't know how to use the the EventProvider class that implements CalendarEventProvider interface .
I don't know how to manipulate the dates startDate & endDate in the method:

public List<CalendarEvent> getEvents(Date startDate, Date endDate) 

Can you please give me an example of how to use it..
Thank you very much