You can do e-Payment for Customs Duty through the ICEGATE portal using the following steps:
1. Visit the ICEGATE portal at https://www.icegate.gov.in/
2. Click on the 'e-payment' option available under the 'Services' tab.
3. Select the 'Customs' option from the list of services.
4. Enter the required details such as the name of the importer/exporter, the port code, the challan number, and the amount to be paid.
5. Verify the details and click on the 'Proceed' button.
6. Choose your preferred payment method such as internet banking or credit/debit card.
7. Enter the payment details and complete the transaction.
8. After the payment is successful, you will receive an electronic receipt, which you can print or save for your records.
Note that you will need to have a valid IEC code and an ICEGATE login ID to use this service. If you do not have these, you can register for them on the ICEGATE portal.