I've never ordered from NB so I can't say for sure what their priming sugar consists of, but you probably got a 4-4.5 oz. package of it.
You'll want to bring 2 cups of water to a boil, then add the 4-4.5 oz pack of priming sugar, stir until dissolved, then boil it for about another 5 minutes or so. Afterwards, you will need to let it cool to 80F or below then put it in your bottling bucket and siphon your beer into your bottling bucket on top of it - this will mix the priming sugar with your beer.
Then bottle, cap, wait 3 weeks and drink!