I'm nearly 20 years old and I don't know how to use mouthwash
It's pretty self explanatory isn't it?
I don't know how to use the thing, my girlfriend has been using it for a year
I don't think you have much to worry about. You could probably teach a newborn how to use mouthwash.
I don't think it's that simple. Mouthwash is hard stuff. You probably have to use a certain type and the right amount.
I think that you should calm down a little bit and just read the instructions if you are confused. I promise, anyone can learn how to use mouthwash.