I wish i had pictures of my old apartment window to show you!!! grrrrrr!
Okay well I'll describe as best I can...
1 tension rod (like 6-7 bucks at walmart)
and thats it!
You fit the tension rod into the window, leaving a little space at the top to push the napkins through.
I had 2 different colored napkins for this, by the way.
I layed down the first set of same-colored napkins like a diamond shape over a hotdog. So that when they layed with gravity they came to a point. like an upsidedown triangle. So after that, I layed a striped set of napkins over top the others, and in between them. (is this getting confusing? its really not!)
Kinda like that top one, but if you stagger the napkins it looks a little more busy and full.
Hope this helps!!!