[Trinity]

I need some help ASAP. My sister's boyfriend needs to do a picture for the front of his recital program and is asking me for advice on lighting and such. I am only a lowly nature photographer and haven't gotten into the people aspect yet.
He's doing the picture with another girl and this attachment is their inspiration. They want to recreate it somehow. I live way too far away to have anything to do with the actually taking of the picture, but I could help with the digital darkroom. I'm not sure how they should set up the lighting and background though. Any ideas?