How can I lighten black hair?

Depends on what hair color you are wanting. You jhave to lighten it little by little. If you are wanting to go straight to blonde then it takes time to get there. Tell me what color you want.

I actually have brown hair and the salon dyed it almost jet black. I would be happy with just light brown or even medium brown at this point. I just want it lighter. I thought maybe if I put a dark blonde on it might lighten it up to brown but I also know that red will appear.

In order to go from black to blonde, it will require a double process (bleaching and toning). If you dye it blonde with a permanent hair color, it will result in a brassy or red/orange look.