This phone does not officially support Android 4.x due to hardware limitations. The latest version to which the firmware is upgradeable is 2.3.6 and it can be done through Samsung Kies. Just download and install the package, and connect your phone. If there is an update available, you will be notified. Additionally, there is a custom port of Cyanogenmod 9 which is based on Android 4.x available for your phone but it's pretty useless since it's just a port and many things don't work.