How do I update my iPad with iOS 5?
If you are using IOS 4, you need to connect to iTune (computer) to update software.
Make sure all contents are transferred and device is backed up before you update.
How to backup
If you have an iPad 2 as your post says, you will end up with iOS 6.1.3 (current version). You cannot update to any earlier version.
Retrieving data ...