Don't worry too much about it's current appearance -the vendor will no doubt blame it on the delivery service.
Java moss is very tough stuff when given the right conditions, I have had tanks so overgrown with the stuff that I had to regularly give away portions to keep it down.
Try this.....Put the moss in a shallow water filled (preferably tank water) container & place on a sunny window sill for approximately a week. It doesn't matter if you cannot heat the water, it will be fine for a short period.
Ignore any algae that develops on the sides of the container, just watch for fresh green growth from the moss, this extra natural light should spur the moss into a growing spree. When you feel confident enough that it is growing again - place back into your tank.
If you are worried about algae - BN's or otocinclus will keep any algae down without damaging the moss.