Clairol basic white powder lightener

Clairol Professional BW Lightener, 16 oz. Product Benefits Creamy consistency, Dedusted to minimize powder fly-away. I’m not a professional hairstylist my hairstylist told me to buy this but she ended up canceling so I had to go see somebody else I don’t know how or what to use this for I just know that it changes the color of extensions to brown from black.