1. Click the UPGRADE NOW button at the top of the screen. 
  2. You can access the details of the package from this screen.
  3. Click on the Add Field Force for Current Subscription Period box.
  4. Update the number of your field force.
  5. Based on the choices you have made, you can see the amount you will pay.
  6. You can then continue to the PAYMENT & INVOICE tab by clicking the NEXT button.
  7. Fill in your payment information.
  8. Select the credit card from the Payment Method part.
  9. After filling the necessary information of your credit card, click the PAY button.