This is a unique way to show off lace #curtains . The top fabric can be an off white such as this, a different color lace, a print fabric or can be a solid color brought in from accents in the room. The pleating is called "Ripple Fold" and I believe is available from Kirsch Hardware or you can accomplish a similar look with grommets.
Removed the hideous window treatment that came with the guest bedroom. The room is kind of dark, so blackout curtains aren't essential. White might be the best choice for brightening it up. (Other than a coat of paint!)