How do I upgrade to ios5?
How do I upgrade my old iPad to ios5?
iPad, iOS 4.3.3
Assuming you have an iPad 1, this process will upgrade it to iOS 5. All other models will upgrade to iOS 7.
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.