Connect your iOS device to your computer, launch iTunes and click “Check for Update.” You can also update from the device itself by going to Settings > General > Software Update.

According to Apple the update contains the following changes:

• Fixes a bug that prevents iPhone 5 from installing software updates wirelessly over the air
• Fixes a bug where horizontal lines may be displayed across the keyboard
• Fixes an issue that could cause camera flash to not go off
• Improves reliability of iPhone 5 and iPod touch (5th generation) when connected to encrypted WPA2 Wi-Fi networks
• Resolves an issue that prevents iPhone from using the cellular network in some instances
• Consolidated the Use Cellular Data switch for iTunes Match
• Fixes a Passcode Lock bug which sometimes allowed access to Passbook pass details from lock screen
• Fixes a bug affecting Exchange meetings