To use WhatsApp Web and Desktop:

1. Open a web browser on your computer and go to web.whatsapp.com
2. Open WhatsApp on your phone and go to the “WhatsApp Web” option in the menu.
3. Use your phone to scan the QR code displayed on the website.
4. Once the QR code has been scanned, your phone and computer will be linked, allowing you to access your chats on your computer.

For WhatsApp Desktop, you can download the app from the official WhatsApp website and install it on your computer. Then, follow steps 2 and 3 to link your phone to the desktop app.