go to a pro,don't even think about doing it yourself.
i got lucky,my mom is a hairdresser and showed me how to bleach it the right way.i've never ever ever tried bleaching my hair,i want to but i don't its way too dangerous. but even a pro can get things a little off,like when my mom bleached my hair 2 years ago so i could have purple chunks with a black halo.....my hair turned orange,so i had to have super bright red dye in there for 2 months until my hair was healthy again....still,it turned orange,then i just waited a week and asked my mom to bleach it again,it was an ugly pale yellow but whatever works to get "my little pony" purple in your hair,i actually miss my super bright red hair,it was like a flame on your head kind of thing.