1. Prepare cake mix according to package directions for cupcakes.
2. While cupcakes cool, cut 24 (4- x 1/2-inch) strips of scrapbooking paper. Write Valentine notes on the plain side of each strip of paper. Beginning with a short side, roll up each strip tightly to hide the note. Set notes aside for now.
3. Spoon frosting into a big bowl, and stir in food coloring, 1 drop at a time, until the color is just what you'd like.
4. Decorate the cupcakes: Spread cupcakes evenly with frosting. Sprinkle with colored sugar. Place 1 round gummy candy on each cupcake. Using picks, attach notes to cupcakes through the round gummy candies.