In order to perform an upgrade of the OS on any Android device, it's advised to have it charged at least 80% and use a stable Internet connection (WiFI preferably). This is advised due to large amount of data that will be downloaded. From your device's menu, go to Settings > About > Software Update > Update. This is the only way you can upgrade your phone OS. However, it seems that the 4.1 version of Android isn't available for your device model. This means that the model hasn't received an official release of the OS yet, and you can't install that version on your device.