Once you have accessed the WhatsApp Web website, you will be required to scan a QR code from your Smartphones' WhatsApp application. To scan this code from your phone;
Open your phone's application menu and scroll to find WhatsApp Application. You could also just search for it if your phone has the search feature.
On the chat Section of the messaging app(WhatsApp), click on the three dots located in the top right corner of the WhatsApp dashboard.
Select the linked devices option. This is what we will use to link our WhatsApp account to the WhatsApp web version. Here if you scroll down, you will be able to see devices or browsers that are linked to your account already. If you have never linked one, this will be empty.
Lick on the "Link device" option, which will open your camera to scan the code. If you receive a prompt from your device asking you to grant WhatsApp permission to use/open your camera, accept it/allow it.
Now scan the QR code on the WhatsApp Web page. If the QR code is not there, click on the "Click to reload QR code" option.
Keep your camera on the QR code until you see a message saying that your device is being linked.
Make sure you keep both devices connected to the internet as WhatsApp web communicates with your Mobile WhatsApp application while transferring Messages and Chats.
Done, you can now continue chatting from WhatsApp Web.