I have a Ipod TOUCH version 4.2.1 how do I update the IOS Systems

If your iDevice is using a version of iOS lower than 5, you will need to use iTunes on your syncing computer to perform the upgrade. Use the Apple link below as a guide for the upgrade.

http://support.apple.com/kb/HT4972

Also read the instructions from the section entitled "Update your device using iTunes" at the link below.

http://support.apple.com/kb/HT4623

Information regarding transferring purchases from your iDevice to iTunes on your syncing computer can be found at the link below.

http://support.apple.com/kb/ht1848

You have a 4G iPod. It will go to 6.1.5 via iTunes. Yo need iTunes 10.7 or later on the computer

iOS 4: Updating your device to iOS 5 or later