Iphone 3 app question?

[Bookworm711]

iOS 3 or 4 is a software update, not an app. You can either download it from iTunes:
1) Create an iTunes account (it's free)
2) Download iTunes from iTunes.com
3)plug your iPhone into your computer and sync it with iTunes
4) when it's synced click on the check for update button
5) It should download and install the update right to your iPhone

You can do it on the phone itself
1) Go to Settings
2) General
3) Software Update
4) Click on the software update that appears on the screen it'll download and install onto your phone as long as you have an iTunes account because that's what is required to operate the apps and software on the phone