There are two ways you can upgrade your OS. You can connect your device to a WiFi network and go to Settings > About > Software Update > Check for updates. By doing this, your device will automatically search and download the latest upgrades available. It's advised to use a WiFi connection because of the large amount of data that needs to be downloaded in case of an upgrade.
To upgrade your OS, you can also use the Upgrade utility that is available to download on the official website. The Armv6 it's the processor of your device. This can't be upgraded due to hardware compatibilities.