Please refer to this link if you are Downloading an app for the first time .
To Un-install an application from your Android device:
- Open all apps.
- Tap on the Settings icon and select Apps
- You will be presented with a list of applications you have installed.
- Select the application you want to uninstall, and click the Uninstall button.
To Download the application to your device again:
- Open the Play Store application in the Applications menu.
- Make sure you sign into your device with the same Google Account you used on your previous phone.
- Press the Menu key then select the My Apps option.
- Click on the application you want to install.
- To install it, just click on the Install button.
- Click on OK to finish installing the application.