There's not much to this how-to from Country Living. Specifically, it says:
"Tightly wrap a doily around a vase. Snip away any excess, then hand-stitch the doily securely in place to create a snug fit."
I do love the freeform look of the lace here. I suspect this design stands or falls on the interestingness of your doily and the shape of your vase. And I wonder about washing the vase if you're using fresh flowers in it.