You can try spreading the dye with using rubbing alcholol, but if that doesn't work, you may have to buy black dye like Rit. You can try using a black sharpie, but I doubt it would look the same like how it was.
School courses, Uni programs or from independent artists that are fluent the field you want to pursue. First try to observe if one is available in your area, if not, then the internet is your friend.