Hairscare is right.
You won't be able to dye dark hair blonde just by using a blonde colourant.
You would have to bleach the dark hair first to lighten it and then use something like the l'oreal to get it to the shade of blonde you want.

Its always easier to buy a piece lighter than your own hair and make it darker than the other way around.
I think hairscare's suggestion of dying your own natural hair darker to match the piece is your best advice.
Colour eventually fades from a piece as would your own hair (if you dyed it).
The two could fade together and then you could tackle it better.