Even after reading these answers it took me a while to figure this out so in Layman's terms:

Click the + button at top right corner, under Vendors column select "Credit Card Credit'.

In the field labeled 'Choose a payee' you're going to select the company that gave you the refund.

Credit card account is the credit card you received the refund on.

Enter the date that the refund went back on your card.

in Account you want to select the same expense account that you charged the original purchase to.

Description, I just put Refund. 

Enter the Amount.

Save and close.

Now go back to your transactions to review and it should be matched up to the CC Credit that you just entered, if not, double check to make sure the payee (vendor), date, account, and amount are all the same.