Welcome, and you've come to the right place to learn and find out how to enjoy your RV to its fullest.
As far as water goes you are going to have two options. One is to fill your onboard water tank which will limit your use of water, and then what should be labeled "city water" which is when the campsite has a water spigot to attach a hose to (make sure it is a freshwater hose only, not a garden hose) that will give you unlimited water. But, the caution here is if you don't have a sewer connection at your campsite you will still be limited to how many gallons of fluid your grey (sinks and shower) and black tanks (toilet only) will hold. Also, do not turn the campsite water on full blast. Many have high pressure or unregulated pressure that could damage a water line. Most folks use a pre-set water pressure regulator to about 40 lbs and available at Walmart and Amazon.
Jackie pretty much summed up the simplicity of the water. Where you will find the biggest use and consequently take up the most room in your "grey" tank, is washing dishes. What my wife and I do is use a dish pan in the sink to wash and rinse dishes, not turning the water on full blast, and then take the collected water in the dish pan and dump it outside. Now, some may say you shouldn't be discarding this "grey" water outside, but water and dish detergent don't hurt anything. You will see many newer campers with outside faucets/showers on the campsite side of the trailer and their owners setting up a wash station where they'll wash the dishes in a dish pan, then rinse right onto the ground, same concept.
With electricity, first off get yourselves some kind of electrical management system;
https://www.amazon.com/Progressive-..._B01N0W4CZ8/?tag=hyprod-20&linkCode=df0&hvadi
to protect your electrical supply from the campground. Next is to monitor your usage in the camper. With a 30A electrical connection, you'll have just over 3000 watts of combined electrical power. You can find charts online to add up what each device you use and how many watts it takes. A couple of examples are your 1500-watt hair dryer and your 1200-watt microwave doesn't leave you much more power to say brew a pot of coffee.
Don't worry, everything will come to you quickly and soon you'll be hitting the road and enjoying your RV with the rest of us.