Warm, shallow water
Once your baby's umbilical cord has fallen off it's time for his first bath.
You can either use a basin with about 2 inches of water or a bath with an infant sling to support baby while he lies down. Use warm, not hot water (most baby stores sell tub thermometers that warn you if it's too hot). Then use a wash cloth and mild soap to clean him. Most importantly never leave the baby unattended.