There isn't a single treatment for colic and no absolute cure. Instead, there are many ways to make baby's (and your) life easier while she/he is colicky.
First of all, you should be sure that there isn't another, simpler cause for baby's discomfort. Check that baby isn't hungry but don't force them to feed if their not interested. If the crying persists and baby isn't hungry, try these tips :
-- Walk around with your baby or sit in a rocking chair; continual movement soothes a baby. Swaying or swinging motions will help too, as will the vibrations from the car while you're driving
-- Try burping your baby more often during feeds. Between feeds, lie baby over across your lap, face down, and rub her/his back gently.
-- Play music. Something slow and gentle, preferably classical.
-- Nestle baby's head in to your neck, just below your jaw, and sing something quiet and monotonous. Babies hear through the vibrations in their skull bones as well as with their ears and they will feel your voice as well as hear it.
-- Lie baby on your (bare) chest, with baby's ear over your heart.
-- For babies who don't like to be cuddled, try holding baby's back against your chest with your hands under their knees. Lean forward, lifting baby's legs away from you, and you'll be able to surround baby without losing view of their face.
-- Warm, gentle pressure on the abdomen will often help too.
Caring for colicky babies can be very frustrating and it's important to take care of yourself too. Make sure you get enough sleep; share the load with your partner or even ask your parents or friends to watch over baby for a few hours while you rest. When baby naps, you should too, no matter what else needs to be done around the house. Baby will outgrow this phase; colic will stop naturally around there months (if it seems to be continuing passed that age, you need to consult your doctor).
Try to develop a routine. Not just for baby's day-to-day needs but also to take into account the colic. If your baby's colic is worse in the afternoons, don't plan to get anything else done during that time and try to get some rest beforehand.