How long do you leave the Bleach in when bleaching your hair MY hair is black and looks almost orange in some spots but at the ends its still dark?

You can leave bleach on the hair for up to an hour. After this it will not work. You have to make a fresh batch. The more time that the bleach is out in the air the less time you have to put it on the hair. The ends are dark because there is more of a build up of colour there. You will have to do this on a few separate occasions. Because your hair is black the bleach will take longer to take the colour out. Black changes to red, the orange then blonde, it does take longer to get black out.