1. Products > Merchandise > +Add (follow steps) > Select "Is this item a gift certificate?"
If you do not see option for "Is this item a gift certificate?", please email email@example.com to open this feature.
> complete other fields > save changes > select advanced settings > Save Changes
2. Change the "Merchandise" tab name: Settings > Custom Labels > Rename Merchandise Tab to something such as "Merchandise and Gift Cards" > Save Changes