How to update to iOS 5.1 from iOS 4.3
How to upgrade to iOS 5.1
iPad, iOS 4.3.3
How to upgrade to iOS 5.1
iPad, iOS 4.3.3
An iPad 1 will be updated to iOS 5.1.1. An iPad 2 and newer will be updated to 7.0.6.
The option to update without the computer (Over the air) was made available with iOS 5. 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.
Update it from iTunes on a computer as described at the bottom of this article; devices running an iOS version prior to 5.0 can't be updated straight from the device. It will be updated to the newest iOS release supported by the device’s hardware, which is iOS 7.0.6 for devices with at least 512MB of RAM.
The maximum iOS version for the third generation iPod touch and original iPad is 5.1.1.
If you don't know what device you have, append the last three characters of its serial number to http://www.everymac.com/ultimate-mac-lookup/?search_keywords= and load the page.
(101539)
Connect your iPad to your Computer using the Usb Sync Cable and with the Help of iTunes you can Update your iOS Version on iPad.
Update your device using iTunes :
http://support.apple.com/kb/ht4623
If you do not have iTunes installed on your computer then install it from here
How to update to iOS 5.1 from iOS 4.3