Im a hair stylist.. First off, How dark are you all over? If your black all over.. you def wont be going blonde for a very, very, very long time. If your a medium brown, you could def get there. The best way to do so is to make it look as natural as possible!.. So, i would recommend going to a salon and telling them to SLICE all of your hair while leaving little hair out of foils with a powerful lightener.
Whoever told you to use Dishliquid Soap...DO NOT DO IT!! its very damaging to the hair!!!! If you do this, then decide to lighten your hair, you could ruin your hair!..
Also, what are your regular routines with your hair.. Do you flat iron?? Do you blow dry often?? If you use lots of heat every day on your hair, you may want to reconsider lightening your hair all over.. UNLESS you buy professional hair care products to protect your hair!!
I hope this helps you
Hopefully you can get to your beautiful blonde that you want