Assuming you are using a relaxer kit, we have these great tips to help guide you when applying your relaxer so you can get great results when you're through
The relaxer may accidentally touch the skin, and cause your skin to burn. Protect it from burns by placing a protective gel such as petroleum all along your hairline and by wearing a pair of latex gloves while relaxing the hair
Section hair into four parts; make one vertical part and a horizontal part in the middle of your hair. Use hair clips to hold three sections
Put some of the relaxer on a tail comb and the section that isn't secured by clips. Part this hair in one inch horizontal sections and apply to this hair section. If you have virgin hair (i.e. hair that hasn't never been chemically processed) then use the tail comb to coat hair from the root to tip.
If your hair has been previously relaxed, the relaxer should be applied to new growth (unprocessed virgin hair) only, about 1/8th of an inch away from the scalp. Do this to the entire section, then move on to each of the other sections.
Next, wait until the time indicated on the box, for relaxing to be completed. However, if severe scalp burns are being experienced then remove the relaxer immediately, first rinse with warm water then cleanse with neutralizing shampoo for about three times.
Otherwise, when the time is up, remove the relaxer in the same manner. Follow with a conditioner and then style hair the way you prefer.