Summarize this article:

It's an app that's often located on the home screen, or you can open the app drawer by pressing the "Apps" icon at the bottom of the screen. On some versions of Android, you can simply swipe up on the home screen. Tap the search bar at the top of the screen and then type steam. Then start the search by tapping the magnifying glass icon on the bottom-right of the keyboard. It should be the first result if you correctly searched for "steam." The app will download and then install automatically. Once the app has downloaded and installed, this opens the app.

Summary:
Open the  Google Play Store. Type steam into the search bar then tap . Locate the Steam app and tap Install. Tap Open.