Leave it to the experts hun. Trust me, your hair will turn a hideous orange colour if you try bleaching your hair at home. Have you considered having your hair stripped? Get all the black out, or most of it out and then start gradually getting blonde foils until your hair is healthy enough to handle all blonde. It's a very time consuming and annoying transition, I know, I did it last year!
My hair was almost black (coloured) and we gradually started putting in blonde foils, adding more and more each time I went back, then eventually started using a lighter colour as a base as well as the blonde foils. It took a few months until I and my hairdresser were happy to do blonde all over, and even though I had achieved the colour I wanted, my hair was in SHOCKING condition. It has taken a lot of deep conditioning treatments to get it back to a healthier condition. Also, be prepared for snapping.
But hey, if it's what you want to do..do it, but it do it properly
