Source: Martha Stewart
Dressing a card as a present is as easy as tying a bow. These ribbon-tied cards can be decorated as simply or as elaborately as you wish. We added a gift tag to a card tied with pink seam binding; on another, "noel" is spelled out in large letters written in opaque white ink.
Card stock folded in half (or a plain store-bought card)
Use a utility knife to make a vertical slit the width of the ribbon in the middle of the card's spine (make the slit higher or lower if you want the bow to be off center).
Thread the ribbon through the slit, and wrap it around the front panel of the card as if wrapping a gift; slip a gift tag on the ribbon, if you wish, and tie a bow in front.