Leave to act. The duration depends on the dye and is specified in the instruction enclosed. If this is not your first application, cover the roots, leave the dye to act for some time /see the instructions/, than apply to the strands, and leave it again.
Before rinsing, pour some water on the hair and gently massage for 1-2 minutes.
For the first washing after hair coloring do not use shampoo, just rinse the dye thoroughly and apply neutralizing conditioner to stop the reaction and to nourish the hair.
You should reapply every four to six weeks, depending on how fast your hair grows to cover the roots and to refresh the color.