Hello and welcome to the Seamly2D forum, @shortylavender
I share the visual thinker with you, so I understand 
Here, I posted a cupcake box pattern that I created. Mostly, drapes are very simple squares with lots of internal paths indicating the pleats, hems, etc. and you will be able to work out and indicate how many are necessary and work out the distances between them. If you actually create the pattern piece for the drape, you will be able to export it from Seamly and import it into InkScape, CorelDraw, Illustrator (in real size) and add dimensions and pattern makings to the diagram to include in the make-up instructions.
It’s difficult to give any real advice, but if you have any questions, we’re a friendly bunch who are really happy to assist, so please don’t hesitate to ask.