If you are hooked up to city water (not a private well), and it is treated at a water treatment facility before reaching you, then it already has chlorine in it. Just fill your fresh water tank and run some through the line. It will self-sanatize.
Now... if your water system is a private well that does not contain chlorine? Well, then you need to add the chlorine yourself. Use a funnel and pour in one cup of bleach at a time into your fresh water tank. Then add water via a garden hose. Otherwise, city water is already treated. It will sanatize your camper. Nothing more to do.