For what it's worth.
Your new so your first "de-winterize" experience should be done at home rather than at the campground (better to be home if you mess something up). I also recommend that you take the time to sanitize your water system as part of the "de-winterizing" process. Fill your tank with water/bleach as other have recommended - allow the bleachy water to flow through the water system - let it sit overnight - then flush out all the water - fill the tank again without bleach and flush lines until no bleach smell.