Black and lavandar hair (?)

Soon i'll be dying my hair dark brown-black. I have razor-layered hair and I want my second layer to be lavandar. So...do I bleach the part I want lavandar? will the bleach go light enough to put lavandar in after dying my hair dark brown-black? or do you think I might have to bleach that part a few times like with quickblue powder. btw, my natural hair color is blonde but is medium brown right now, if that makes a difference.
Thanks to anyone that can help.

Good luck!

I would recommend having this done professionally, but if you'd rather do it at home:
If you have dye on your hair already, you'll need to strip that completely off, which is very damaging, not to discourage you. You can buy haircolor stripper (whatever they call it) anywhere - grocery store, beauty supply, pharmacy, etc.
Stripping your hair, especially with dye on it, will turn it orange. You can bleach that out afterwards to get it good and ready for the lavendar, but don't do it right away. Wait for at least 24 hours (and I'd wait even longer)before bleaching it again.
It will be pretty damaged, so the temporary color (Manic Panic or something similar) will work really well.

Wow!

that sounds really cool!
I'd be scared to do it at home though. I reckon you should bleach first.