First, brush and floss as you normally do.
Place one tablet in your mouth, chew it, and allow it to mix with your saliva.
Swish the mixture in your mouth for about 30 seconds. Run some water in your sink, then spit out the solution into the running water. (Running the water helps ensure that you don't stain your sink).
Then, examine your teeth for plaque colored by the dye. Because the dye stains all bacteria, your tongue and gums also may get stained and remain stained until you brush your teeth a few times. Older plaque is stained blue, and newer plaque is stained red. Anything that is stained contains bacteria, and is considered not properly cleaned. So, the next time you brush your teeth, pay special attention to these areas.