Usually, Windows 8 automatically add tiles to the Start screen for almost all the application / program you install. But still, if the tile is not added you can manually add it to your Start screen. Follow the steps provided in this tutorial to add tiles to Windows 8.
Creating and adding more useful tiles
1. Move your mouse pointer over the lower-left cornor of your screen. Select Search from the charm.
2. Next, all the Application / Programs that you have installed on your computer are listed in alphabetical order in the left pane. Scroll to the right to see the complete programs. You can even search program by typing program name in Search box on the right pane. Right click on the application / program icon. Next, you will see an option bar at the bottom. Click on Pin.
3. Finally, you will see the tiles on your Start screen. That are the complete steps to add tiles to Windows 8.
With new tile features in Windows 8, you can access your application / programs instantly. The tiles are shown in the Start Screen.