it should heal by itself, depending on deep and long the cut is of course... bathe with warm salt water as above and cover it with some sort of clean dressing (you can get from a pharmacy) and keep it clean and dry. If you notice any swelling, redness, pus or offensive odour coming from the wound or if it becomes more painful see a doctor as you might need antibiotics. Also are your tetanus vaccinations up to date?
ouch!
it will heal on its own but bathe it in warm salt water ... it will stop it from getting infected.