To connect, open the app and you will see a QR code, simply scan this code using WhatsApp on your phone and you will be logged in. You will find this option within WhatsApp settings on your phone, at "WhatsApp Web" menu.
Disclaimer
This is an UNOFFICIAL tool for WhatsApp Messenger. This app is developed by an independent developer, not affiliated to the official developer. Usage in this app falls within guidelines of "fair use".