How can i update my ipad to ios 5?
Update it from iTunes on a computer as described at the bottom of this article. As it's running an iOS version prior to 5.0, there won't be an option to update from the device itself.
I don't think that could happen, because Apple only supports updating to the latest iOS version (iOS 6.1.3)
If the poster wants to update to iOS 5 and no further then this can't be done on an iPad 2 (if that's what the poster actually has).
An iPad 2 (or later) can only be updated to iOS 6.1.3 following the procedure that Niel posted.
An iPad 1 can be updated to iOS 5.1.1.
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