Most babies get nappy rash at one time or another and if your baby succumbs it doesn't mean you're a bad parent.
'Nappy rash' is a catch-all phrase that encompasses a multitude of skin conditions.
The two major causes are either the body's naturally occurring fungus thriving in warm damp conditions or the reaction between wee and poo. Ammonia is created if wee and poo are in contact for some time and attacks the baby's delicate skin.
In both these cases, it is recommended that you change the baby frequently, washing with warm water and pat drying thoroughly.