Purchase a paint, preferably a professional. It is better to discolor the hair, as well as less traumatic effect on the structure and hair follicles. If you cannot find the required drug, consult with an experienced hairdresser. By the way, to lighten the roots can be in the beauty salon that is much more preferable.
If you use regular paint, dispense half of the money from each tube in a porcelain or glass bowl, mix thoroughly. You need to use immediately. If you have acquired a professional clarifier, the required proportions refer to the instructions for use.
Put on gloves and proceed to the discoloration of the roots. Start apply the mixture with the back of the head, trying not to fall on previously colored hair. For ease of application use a special wide brush, not a toothbrush or applicator bottle. If you are not able to carry out such a procedure, ask someone close to help you.
Note the time required for staining. 5-10 minutes before you will need to wash off the paint, and spread it throughout the length to refresh the colour of hair. Don't forget to apply a nourishing balm that softens bleached hair and nourishes throughout.