I don't know why you get downvoted. If they are a complete beginner, they should go to https://developer.android.com/guide https://developer.android.com/guide a

I don't know why you get downvoted. If they are a complete beginner, they should go to https://developer.android.com/guide https://developer.android.com/guide and first learn about the concepts such as Intents, Resources, Android Manifest, Activities/Fragments etc. It's all there in one place.