You can lighten your hair quite a bit if you spritz it with lemon juice and go out in the sunlight (this is an old trick my grandmother taught me, and works best in summer). If you want to darken it...
Depending on the number of the dye, it may be semipermanent, a rinse, or permanent. Read the box to find out which one it is. For all but permanent, over time, shampooing will remove the dye. If the...