Hello! Can you please tell me about bleaching hair with hydrogen peroxide. how long must it remain on hair and where can you get some? i think the proper kind or grade to use is the”beautician grade”. is there any alternative?

(may be broke/outdated!)
Hello! Can you please tell me about bleaching hair with hydrogen peroxide. how long must it remain on hair and where can you get some? i think the proper kind or grade to use is the”beautician grade”. is there any alternative?