I don't have an update icon
I need to update my iPad but when I go to the settings menu and touch general there isn't an update icon.
iPad 2 Wi-Fi
That is only a feature of iOS 5 or later...
If you have iOS 4... See Here...
http://support.apple.com/kb/HT4972
OR...
Connect to iTunes on the computer you usually Sync with and “ Check for Updates “...
See the Using iTunes Section Here...