How to I update my iPod touch 5th generation to iOS 10 ?
iPod touch 5th generation
You can't. Your iPod touch only supports up to iOS 9.3.5.
As an aside, these are the Developer Forums where developers of apps for Apple's platforms ask each other for hints and tips on coding.
Your question was more of a product support one, so I'd suggest you ask such future questions over at the Apple Support Forums. Thanks.