Download whatsapp for PC and enjoy the App on your Desktop or notebook. All you need to do is download a software called BlueStacks witch is possible to simulate an Android environment witch one is compatible with Whatsapp. You will need a valid phone number too. Remember that you can´t handle the same number of your smartphone (already registered with Whatsapp), because the app does not allow the same number registered twice.
After installing BlueStacks you will need to log in with a Google account and you will be able to access the Google Play Store, search for Whatsapp, download it, accept the license terms, add a valid (and not registered yet with whatsapp) phone number and voila. You can use normally whatsapp on your PC or notebook.