Love this blog,found it a year or so ago and did this system to span a large area on our back porch. Used Painters drop cloths with hanging clips for curtains with a chain sewn in the bottom hem for weight!
DIY:: So Simple !! Pottery barn Inspired Curtains These could be made from flat sheets or white fabric painters drop cloth with Gross grain ribbons sewn onto the top....for a very simple solution to cover a window. Could also be tied back with gross grain ribbon when you want to let the light in.