FInd a place to fit LOTS of people get a projector a good movie and a sheet.
Find an open area like your front yard, back yard, etc. Pick up a popular movie or a couple and have the guests vote on which one they want to watch. Get a tarp and some tables for a concession booth(don’t forget to buy drinks, candy, popcorn, really anything you want to sell there) make sure to advertise the night well with flyers and ads in you local newspaper. Now the hard part(this is optional) get lots of sheets or fabric and border you entire “theater” so that there is no light pollution coming from the outside world. Be sure to check with the movie copyright owner for permission.
Alternatively, you could see about renting out a movie theater or asking them to let you show something for free.