HT4623: Update your iPhone, iPad, or iPod touchLearn about Update your iPhone, iPad, or iPod touch
Currently Being ModeratedApr 27, 2012 10:49 AM (in response to ben1064)
Software update only exists on iOS 5.0 and higher.
If you're not on 5.x yet, it won't be there. You must upgrade with your computer.
Currently Being ModeratedApr 27, 2012 10:53 AM (in response to ben1064)
First Connect your phone to your computer through the data cable.
Itunes will detect that the phone in not updated yet and hence it will ask for the update to your current OS.
Update it to iOS 5.1 because that is the latest and greatest OS.
After that update, you will hace a Software update button in the About Section.
Hope it will solve your issue.