How to add fresh water tank sanitizer

[JayJay]

I'm so new I squeak. Please don't criticize. I have gone over the manual to disinfect. I get the bleach ratio part. What I don't get are three things:
1. where do I put the water?
2. do I have to turn on the water pump?
3. where do I drain from? The septic system for gray and black water?

I just bought a used 2006 Winnebago View 23h
Yes, I have read the manual. I am just not getting it.

With much gratitude,