Add the WA approved Template message to Salesforce to Use it:

To use the Whatsapp approved template messages, We should add it first in the WA Template Object in Salesforce

Steps:

• Open the WA Template Object
• create new record
• Name: the approved WA template name 
  
• Request body: the request body of the approved template
  
• Template Content: the Content of the message

ex:

• Name: hello_world.
• Request body: { "messaging_product": "whatsapp","to": "whatsappNumber","type": "template","template": {"name": "hello_world","language": {"code": "en_US"}}} .
• Content: Hello World
  Welcome and congratulations!! This message demonstrates your ability to send a WhatsApp message notification from the Cloud API, hosted by Meta. Thank you for taking the time to test with us.
• Save, then you will find it in the dropdown box of the LWC to send it as a template message.