I have been dying my hair black for a year I want to get the color out how do I do that

You bleach it to strip it of the color, and then put a different pigment into it. It should be done professionally. Even for professionals it can be a difficult task. If you want to dye your hair lighter, this is the only way to do it.

Yeah stripping is really the only immediate option, it's a long process thought it involves bleaching, washing it out, bleaching, washing it out, bleaching, washing it out, bleaching, washing it out, and many more times depending on how the color looks. Not only is it long but can irritate the scalp and damage your hair pretty bad in some cases large chunks can fall out, if you do go with this method bring books and magazines to keep yourself company and lunch :)
Another option is to just let your hair fade naturally and color it when it gets light enough.
Another option (what I did ) is go to a beauty supply store and buy color specifically for dark hair ( I got magenta - highlights ) and color your black hair it will make it light, if your satisfied with what ever color you picked then great other wise wait a bit and color it whatever color you want after that...