It's easy! Isn't tongue brushing for bad breath so tough? It makes you gag, takes time, and is tiring, so I saw an ad and bought it. Just put it on the bottom before brushing your teeth, let it sit for about 10 seconds, then apply toothpaste as usual and brush your teeth. Of course, the foaming power increases while you brush your teeth, so it makes your mouth feel thicker than usual, but I like the feeling of it leaving your tongue nice and smooth without any unpleasant irritation.