It's for all hair colors!
Just make sure to shake well before use. Section off your hair, hold the can 6-10 inches away and spray onto roots. Wait 30 seconds and brush or massage through with your fingertips.
I have auburn hair. I've only used the Hask Chia Seed dry shampoo and I love it. It isn't completely clear. But doesn't leave much residue behind at all so I don't end up looking like I powdered my head. Plus, a little goes a long way. I think it would work great for light brown hair. And it smells fantastic!
I'm not a stylist so I cannot give professional advice. Personally, I would flat iron first and then go in with the dry shampoo. The natural oils help protect our hair and after using heat, I usually find I don't need as much dry shampoo.