Rinse the inside with a mixture of three parts water and one part vinegar. Rinse with clean water; let dry. Drip one or several colors of acrylic paint into the ornament and swirl gently to achieve the desired effect. Let the paint dry and add additional swirls in different colors.
I think this is what you're looking for, Connie:
Hi Connie, here is a great little video on how to do it. It's really easy...