There are three different methods that will allow you to maually update your Android device. With the first method you must connect your device to a wifi, open the settings, scroll down to "about device", tap software update and then update now. If you tap check for updates your device will scan for updates and if it finds any you can choose update now. For the second method you can use your computer to update your device, You will have to visit your manufacturer's official website and search for updates.
If there are updates for your device you can then connect your device to the computer through USB, open teh device managment application and click on the updates you want to install. The third way is to update using a rooted ROM. For this method you will want to backup your device, find online rooting software, connect your device to your computer and download the rooting software. Start the process, and when it is finishes, you need to restart your phone.