I need a little overlay help

So i have been trying to figure out how i can have the mc of my story transform her hair color from her roots rapidly spreading down but when i went into pixlr a (photo editing app) i did it just how i liked it but whenever i put it on episode it isn’t an overlay by that i mean it isn’t transparent because i aign’t no artist so when her hair has a chuck of white (the color im trying to change the hair to) its a big problem for me

Send over The photo I can make it transparent