How do you set up WIFI for a Campground?

I am a manager of a small RV Park located near cities but also relatively secluded. I have many people asking me for WIFI as if it is this simple thing I can just magically get. I'm no where near an expert on WIFI networks or maybe any other options I would have to provide Internet to the campers. I'm wondering if someone can explain my options in layman terms, providing what the cost would be, who I contact, how much work it is, etc...