I want to dye my hair black with blonde highlights. Right now its red on the top and black underneath. I have the blonde dye that will bleach the red. But when would I do the black? When the blonde is in the foil? But who do I keep the black from running wit the blonde?

When you are doing something as dramatic and precise as black with blonde highlights, you will more than likely want to have it done professionally. Hair dye can react with nearly anything- such as hair dye you currently have, shampoo you use, minerals in the water you wash your hair with, etc. When you are going from red to black, to avoid any messes or regrets, it would be worth the money to get it done professionally.