On the last step of the gift campaign wizard, is the payment step. You will have a drop down list of available Funding Sources that have sufficient balance to pay for your gifts.

Once you select the funding source and the order is submitted to Benolo, the order amount will be deducted from the balance of the funding source.

Example: If your starting balance for the funding source is 5000 credits and your campaign costs 3000 credits, your new available balance is 2000 credits.