Rather than go through the whole thing (mainly because I may not remember it correctly, and I don't want to go out to the coach to find the book), I will simply recommend that you find the instructions in your Owners Manual Package for treating the water system.
Or, you could do a search of the topics on these forums that have appeared in the past.
But, basically, you add a certain amount of chlorine bleach to the tank, fill it, run the solution through all the lines, let it sit overnight, then drain, flush, and fill.
I don't remember how much chlorine bleach is recommended.
We have a well, and I only do this once a year.