First I start by piping a border on each cookie a little bigger than the transfer, the royal icing consistency should be sturdy enough that it does not spread on its own. Once done flood the inside of your border, your royal icing should be a little runnier for this, spread out evenly with in the border to make as flat and even as possible, moving quickly place the cut out transfer into the wet royal icing. Gently press the transfer onto the icing so it adheres and let dry. Next the fun part, the decorative border. Color your royal icing as you wish and make it a stiff consistency so it holds it piped shape, then garnish with sprinkles. Let dry.