Currently Being ModeratedFeb 7, 2013 7:07 AM (in response to Hubert irwin)
You can't install iOS 4.3. If you have an iPad 1 you can install iOS 5.1.1 otherwise it's iOS 6.1
To update you will have to connect your iPad to iTunes on a computer (preferably the one you sync with and backup to).
See here: http://support.apple.com/kb/HT4972