In the Account Packages panel to the right of the packages heading click theicon
On the pop-up that appears specify the Bill Run configuration to use to bill this account (bill runs can be configured with various options e.g. bill packages, bill usage, collect payment, send invoices, etc.)
If you want to run billing now select Schedule Now otherwise in the Schedule Date/Time field specify when the account should be billed
Click Run
A message should appear indicating that the bill run has been scheduled, followed by a bill run completion message. Account-packages that are billed will have their 'Next Bill Date' incremented. This date is shown in the Account Packages panel. The 'Billed Through' fields will also be updated on the Billing Settings tab for each billed account-package. You can also check the transactions tab to see new charges generated by the bill run and stamped with an invoice ID