Well. Uh. I used this tutorial and while the instructions were pretty clear, this style is just not for me. And the stripes should go vertically.
It looks okay in the photo, but what you can't see is just how narrow the bottom of the skirt really is. Stairs are kinda hard. I think of Thomas Edison, who said (according to the internet) "I have not failed. I've just found 10,000 ways that won't work."