Package name & Class Name of facebook app

Just a small confusion I want to ask while making a facebook app to implement share feature in my android app Unique app Identifier used to open your app - Package Name: Is it that unique identifier that I have written while creating the new facebook app at their developer console ? or Is it the package name of my android app ? The Main Activity you want Facebook to launch - Class Name: I have added a facebook share button in every fragment(class), so which class is the Main Activity that it want facebook to launch ? Or is it the main activity of my android app?