We bought wooden dowels and Styrofoam balls (these are quite expensive so if you can think of something else, use it). I took a trip to the thrift store for white sheets. I took the balls and inserted the dowel into each one (I had 4). Then I stuck them into the ground in the yard in a circle.
*This doesn’t work well with just 4, I recommend using at least 6.
I had one sheet for each ghost. Draping the sheets over the balls was easy enough, what was hard was figuring out how to keep them there while still having the ghostly effect. I ended up using sewing pins to keep the sheet attached to the balls. I took the corners of the sheets and tied them together to make it appear like the ghosts were holding hands. Now, if you get a sheet in the right size, it should appear that the ghosts are floating, meaning you can’t see the dowel sticking in the ground. Even with the sheets pinned on, they still blew around and even took the ball off the dowel on several occasions. And they weren't very weather friendly.
Definitely a few lessons learned with this experience. I love the concept, implementing it successfully is rather difficult though.
I have come across instructions for something of this nature and they used white trash bags stuffed with newspaper or leaves (this sounds like a much better and more cost effective idea). They tied twine or something similar around the neck of each ghost to keep it attached to the dowel. Tie the ends of the trash bags together and you have floating ghosts dancing in a circle. This year I will be using the white trash bag idea with 6 ghosts and placing them around the trunk of a big tree in my front yard.