Using your second decorating bag insert the Wilton 1M tip.
You can find this tip in any cake decorating isle at a grocery or craft store.. Fill this bag with your easy whipped cream frosting and pipe onto the cupcakes. I like to start at the center of the cupcakes and move in a clockwise pattern out to the edges of the cupcake and then layer up, while still piping on the frosting in a clockwise motion. Depending on how big you make your frosting swirls you may need a second batch of frosting.