Before you aim that bottle of color towards your scalp, you’ll need to carry out a skin test - it’ll help determine if you’re going to have any allergic reaction to your dye. You’ll need to do this at least 48 hours before you dye your hair. If you don’t have any negative reactions, you’re good to go.
Dye instructions will vary according to the brand and color you’re using, so be sure to follow the instructions provided in your kit. In brief, you’ll need to mix the color and developer in your kit, apply it to your dry hair starting at the root, wait for it to do its thing, rinse it out, massage in the conditioner that comes in your pack, then rinse and style your hair.