Set the colored frostings aside so that they firm up and become brighter in color.
In the meantime, slide 12 of the cupcakes to the side of the board. These are your blue section. It helps to move them away from the rest of the cake.
Now it is time for the base. Put some white frosting (straight from the can) into a decorating bag. I used the largest tip I had...the size and shape of the tip doesn't matter because the frosting just has to be piped all over the cupcakes. After the cupcakes are covered, start spreading.