A christening, by definition, is a time when a child is baptized and given a new name as a part of the Christian church. This event is usually a very big ordeal and can become something so important that families even throw a party for the child being christened. At a typical christening, only the very close friends and family members will be invited.
You may choose to have your child wear a traditional baptismal gown. In some families the baptismal gown is passed on from generation to generation. If your family does not have one, there are plenty of stores that still sell them.