If they are live....Here is my mix:
1 cup - RO/DI water
1 tbsp - baby food sweet potatoes
1 tbsp - baby food sweet peas
1 mL - Selcon
1 mL - Vita-Chem
Shake it up real well, then add enough to the culture tank to tint the water slightly. I haven't tried to grow the brine shrimp out for much longer than a week or a bit more. To do so, a different food might be more effective. Also, watch for the culture water to foul, if you don't change it every 3-4 days it will get pretty stinky with bacteria growth.
If they are frozen....first, just buy the pre- gut-loaded kind. Second, just soak them in some Selcon and Vita-chem for a few minutes.