What color base do i use to add brown streaks to already platinum hair?

i want to darken streaks in my hair (framing my face) that my hairdresser did. My hair is platinum blonde with light brown framing my face. How do i know what color base i need when i purchase the dye to mix with developer? Neutral Base, Violet Base? I have no clue about Brown Hair Dyes. Also is it even parts of Dye to Developer?

What color base do i use to add brown streaks to already platinum hair?
YOUR HAIR WILL NEED TO BE FILLED FIRST. IT WILL FADE IF YOU JUST USE COLOR VIOLET IT WILL LOOK MUDDY, RED COULD GO PINK, GREEN WILL LOOK LIKE SEA WEED. PAY TO GET IT DONE THEY WILL MAKE SURE IT WILL LOOK BEAUTIFUL.
Reply:You shouldn't do it yourself, but if you insist, you do not need to add anything your stylist has already added a filler and base color to your hair, it will not turn any funky colors on you when you color over htose parts that are already colored brown.