How do I darken my hair after it dyed too blonde?

You have two or three options with this. You could go get a darker shade and put over the blonde you all ready have. You could leave it alone and it will naurally fade and grow out. You could go to a beauty shop and let a professional fix it. Finally, wear a hat. I have made this same mistake and have used all the above solutions. The dye over dye sometimes really makes it worse. Best bet is let is grow and fade.