Make sure your phone is connected to wi-fi. Simply pull down the notification area and press the leftmost button named Wi-Fi. Alternately you could do this using mobile data but this could get expensive if you are not on a data plan with your operator. Press the apps icon to take you to your apps. Find and press the settings icon to take you to the settings menu. Scroll down to the bottom of the screen and press the About Device. At the top there is a tab named Software update, press it. On the next screen there is a tab named Update, press that one. Your phone will now connect to the Samsung servers and if there is a update available the upgrade should start imminently.