Important question

I guess I'm just nervous of it turning my hair green or something lol

If your hair is already so light, don't use box dyes.  What colour are you trying to achieve? Did you tone your hair white or was it over bleached?

Yes i bleached it too light but I want it the color of the girl in the picture

Whoa. Stop right there. If your hair is LIGHTER than the box dye, that's even more reason to stay a million miles away from it!

It might make your hair that colour, but with a ton of damage you really don't need if you bleached lighter than that, that's already beached to the point of being too much.

You just need a blond toner. What country are you in?

I'm in the United States I can go to Sally's but what do u suggest

When the purple shampoo fades it's like a white/highlighter yellow color, I want it to be a more creamy blonde

Can you get Wella Colour fresh? (NOT colour charm, or colour touch) they are non oxidative dyes that come in a range of blonde shades. Or Roux rinses, they are also handy for tweaking blonde tones, and wash straight out.
I think you are over thinking the whole blonde thing though. You keep wanting to change the colour by the tiniest amounts, that won't be noticeable to anyone else.