Good morning is Bonjour. You can sometimes say Bonne matinée! meaning Have a good morning! ("matin" and "matinée" are both translated by "morning". Use matin when it's about a unit of time and matinée when indicating a duration.) http://french.about.com/library/weekly/aa070100.htm

you can say ( Bonjour )

But... if you're saying "Bonne matinée", it's if you will see again the person in the day... (sorry for my english) Here is my answer : http://www.italki.com/answers/question/21762.htm (But it's in french...)

good morning = Bonjour

Bon matin