First, click the "Customers" link in the left-hand navigation menu, select the customer you wish to take a payment from and then click "Payments" in the sub-navigation menu.
From there, click the "Take Payment" button at the top-right of the Payment History panel. Enter the amount to bill in the "Amount" field and make sure the "Provider" field is set to "GoCardless". The "Collection date" is an optional field, clicking the field will present you with a calendar that you can select a future date from and the payment will be taken on this date. If you wish to take the payment immediately, leave this field blank.
NOTE: The "Collection date" is only usable with providers that support the ability to set collection dates in the future.
Following this a payment will appear in respective Payment History lists with the status of "Pending Submitted" with a charge date based on the "Collection period after invoice issue date" value in Payment Collection Settings.
To access your Payment Collection Settings, click "Settings" in the left-hand navigation menu and then "Payment Collection" in the drop-down menu that subsequently opens.