How can i get my hair this colour?!?

it seems like it's just a blue-black color, so that hair dye comes in lots of different trustworthy brands. Live Color works great, and they have both natural and unnatural colors. If the color in the picture is a blue, then I would say use either Live or Directions, they're both great brands. As to how, if it's really blue, I would say get bleach and toner and do that, then dye your hair. Otherwise, you can try putting the blue-black over it, but I'm not sure if it would work. If you bleach your hair first, it will definitely work, but otherwise I can't make any guarantees. I hope this was helpful, and good luck!