From the Home screen, go to the Store by scrolling to the right by pressing the RB button on the controller.
Next, select Apps.
Here you will see Featured, Popular, and Newly-released Apps.
Clicking on the ellipsis (...) will show more apps from the category above.
You can also select the Search Apps function if you are looking for a specific app.
Once an app is downloaded, it will install and be available from this menu.
3. Open App
Open an installed App from your Home screen by selecting it, then press the A button.
If you want to see other installed Games and Apps on your Xbox One:
From the Home screen select My Games & Apps and press the A button.
From here you can select any Game or App the you wish to launch.
4. Pin or Unpin App
Pin an App
From the home screen, open My games & apps.
Highlight the app you wish to make a shortcut to the home screen.
Push Menu
on the controller.
Select Pin to Home.
Unpin an App
Highlight the app from the home screen
Push Menu
on the controller.
Select Unpin.
5. Snap App
Snapping an App
While in any game, tap on the Xbox Guide/Home button to put it in a window.
Push Left on the Left analog stick to open the menu and push Down until you reach the Snap icon.
Once the Snap icon is highlighted, you can use the Left analog stick on the controller to point Left, then point up or down to choose from available apps. Press A to snap the selected app.
This will show your game and the other app side-by-side on the screen.
To switch which app is controlled, tap the Xbox Guide/Home button to zoom out and use the Left analog stick to select the window you wish to control.