There are two paths for upgrading your current iPhone to iOS 6: over the air or through iTunes.
If you didn't line up at your local Apple Store or preorder an iPhone 5, you can still upgrade youriPhone,iPad, and iPod Touch to the latest version of iOS released today. I should say it's likely you can upgrade your current device because the new version of Apple's mobile operating system, iOS 6, is compatible with most but not all previous-generation devices.
You have two methods for downloading and installing iOS 6. You can simply update your iOS device over the air via the device's Settings, or you can connect it to your computer and use iTunes.
Method 1: Over the air
The easier of the methods is to grab your iPhone, iPad, or iPod Touch and update wirelessly. Before doing so, however, it's wouldn't be a bad idea to sync your device with iTunes if you haven't done so in a while. There have been instances with past iOS updates where users have reported the new iOS didn't install correctly, bricking their phone and forcing them to restore their phone before trying again. So, if your iOS device has talked to iTunes recently, go ahead and go to Settings > General > Software Update.