How to update my iPhone 3GS to iOS 5?

Well I don't have to update my iPhone but I use it as an iPod but it is out of service or if anyone knows how to jailbreak it for free that would be better oh yeah I don't have a computer so I'm doing all of this with Wi-Fi so I can't do anything that needs a computer is there any other way I can do it fast and simple cause I'm not the smartest person ever.

You can't.
I already tried: P

The 3gs can be updated to iOS 6 with using itunes