I never recommend doing lightening processes yourself. The correct formula is critical. I recommend salon schools often. The students take their time and only do what the instructor tells them to do. I also recommend going to one that uses olaplex products. If you do this on your own depending on what processes are on your hair already you could end up orange and fried. Usually a toner is necessary which you can’t predict what formula you will need beforehand. I was a licensed cosmetologist years ago.

I used to have blonde hair with black underneath. Ive done it probably 3x before. I used to always change my hair color Bleach your black hair. The part you want to have blonde. Tie the part you are keeping black apart from the other. Make sure you deep condition after the bleach then do the blonde dye. And for a few months aftet you dye it i would deep condition every few weeks.