Using a gift card/voucher to capture a payment is very similar to capturing a payment for any other payment method. The only difference is that you will be required to input the gift card/voucher code that is being used at the time of payment.

From the account screen (where payments are captured), click on 'Add Payment':

Once you have confirmed the amount and any tip, change the payment method to 'Gift Card'. When you do this, a field will appear asking you for the gift card/voucher code:

As you type in either the client name or the gift card code, you will see the available gift cards appear, with their remaining balance. Click on the gift card/voucher you want to use, and click on 'Add Payment':