Answer:
1. Open a cloud installer (the source), which is usually Play Store, Aptoide, or UpToDown, in the case of Android phones.
2. Request the package from the server, which will be transmitted via an internet connection. Usually called "downloading".
3. Allow the package provider (mobile store) to install the app on the system, this being the "install" part, where it's put together.
4. Run the app by, usually, pressing the icon in the app drawer.