First, you need to add the products that you want to buy to the cart, and proceed to the next.

Then, you add your email ID, Shipping address, and mobile number (only one) correctly, and proceed to the payment page. 

Then left as it is, and you don't need to pay. What you can do now is let us now on the email or do a call or sent a Whatsapp message to the mobile nu,ber +91 8293826607 that you want the COD stating your registered email ID and name.