Is this something you're planning on doing yourself, or are you going to be going to the salon? The good news is, if you google on Victorian hairstyles, you'll find tons of stuff. The bad news is that Victorian hairstyles, especially from the period you're looking at, were anything but simple and easy to do. With waist-length hair, the woman would have had a rat pinned on top of her head and covered with her hair. Then she probably would have pinned curls around the front (either real or false ones) and false long sausage curls down the back.

It's probably a little late to shop for these additions and accessories.

I suggest you take the envelope in to a stylist and let them put up your hair in something vaguely resembling the model's hair.

Snick - Welcome.  Very pretty dress, and you made it! That makes it so special too.  I'm sorry I don't have much help for your hairstyle.  I think eKatherine's idea is a good one.  Try the library for some hairstyle books, too.  Have fun at your prom!