1. Connect to Wi-Fi
2. Connect your USB charger to your phone and make sure it's charging (your battery should be at least 50% charged before software update)
3. Go to Settings > System > Advanced > Software Update > Check For Updates
4. Once the download is complete, you'll receive a Reboot option. Tap on Reboot.
Once you've completed these steps your phone should now be on the most up to date software.