NOTE: 7 Steps (Not so tough..I made them easiest)
Internet required on Mobile and PC/Laptop
A cup of tea :-)
Step 1 >> Open https://web.whatsapp.com in your web browser.
Step 2 >> Launch WhatsApp on your phone and access the settings menu (click the three dots at the top right to access more options on an Android device), then choose WhatsApp Web.
Step 3 >> A QR reader will then open on your phone; point this at your PC screen to read the code and be automatically logged into WhatsApp on the web.
Step 4 >> The interface will be familiar to WhatsApp phone users, but you should note that desktop notifications are supported, which you may want to switch off in the settings menu for privacy reasons if this is a shared PC. As on the phone, tapping the three-dot icon brings up more options. Select Notifications and then deselect Desktop Alerts and Sounds.
Step 5 >> Starting a new conversation is slightly different on the desktop. As on the phone you can click the new message icon to select one of your contacts, but in WhatsApp on the web the search function lets you start new conversations as well as filter existing chats.
Step 6 >> Within a conversation the interface matches that of the phone, with emoticon and Mic icons sitting either side of the bottom text-entry field, and a paperclip icon at the top to attach files. Beside this is a more options icon that lets you view contact info. And as on the phone you get the single-, twin- and blue-tick system to show whether messages have been sent, delivered and read.
Step 7 >> Once your phone and computer are connected you are able to manage your logged in computers from your phone via the Options, WhatsApp on the web menu. From here you can log out from all computers, or you can use the options menu in WhatsApp on the web to log out from the PC you're currently using. WhatsApp will by default keep you logged in unless you specify otherwise, but having logged out you'll need to go through the QR code process again the next time you want to log into WhatsApp on that machine.
Messages between phone and browser are instantly synced, so users on limited mobile data contracts should be wary of increased data usage. It's a good idea to switch on your WI-Fi if you're a heavy WhatsApp user.