You can add payment details in the sale transaction.
1. Go to Transaction > Sale.
2. Fill the transaction details.
3. Click on tab of Payment Details.
4. Fill the details of payment.
Net Amount: Net Amount will be fixed rate of the item. You cannot change it.
Payment by: Select the ledger(Bank Account type) by payment will be done.
Payment mode: Select the mode of payment.
Payment :: Amount: Enter Amount have to pay.
No. of credit days: Enter number of credit days.
Click on OK/Apply button.