1 ?g(microgram) per gram = 1 ppm (points per million)
So that means you'll have to check how many micrograms of NaCl you've got there. Then, you'll have make an assumption that the density of that solution is 1g/ml, which gives you 50 grams of solution.
Divide the micrograms of NaCl by 50 g of the solution and you've got yourself ppm's