Apps Android Tablet

[AndroidDevleop]

Hi, I have developed a app in Android 2.1 which is for Android phones. When i try to install the same app in Android Tablet 3.0, I found the application is loaded by taking the full width and height of the tablet but i want it to get displayed at center with the original app size(smaller size). Please suggest what code changes are required to achieve this.

Thanks,
Android Developer