You can send money after you have added your bank account to WhatsApp
Follow these steps to send money:
STEP 1: Open a chat with the person you want to send money to.
STEP 2: Tap the payment icon.
STEP 3: Enter the amount that you have to send > tap next > Send.
STEP 4: Verify the payment by entering your UPI PIN.
Note: Once the payment is sent, the transaction details will be listed in the chat, including a transaction ID.