General Steps:

Before Selling Gift cards to your clients you will need to Setup Gift Cards into your system ,  after being all set now this process can be done from the front register:

• Click on Register Tab
• Navigate to Action Menu (right panel). from the Transaction Tab, Select "Sell Gift Cards" option.
• fill in the gift card number or you can simply Scan the card.
• click 'ok'.

Finally enter an amount of  price that you want to sell the gift card for.

also make sure to add a customer (optional), whom you are selling the card to, this will later create on their profile that they have the possibility to pay an item from your Store with their Gift Card.