Important requirement to begin with is you need a Rooted Phone. In case, you have different Mobile phone then use Universal Rooting Tools like Z4Root, Super One click Root or Universal Androot App.
How to find APK File Location :
On a rooted Android phone, Download Root Explorer or a free alternative Android Root File manager ES File Explorer.
In case, you are using ES File Explorer, go to settings and enable “Root Explorer” option to get access to Root Directories.
Go to location address – /data/app/ where all APK installer files of installed application downloaded from Android Market or Amazon App store.