So, Here is the intruction how to get or update your iOS 5:
Step 1:First of all to update or upgrade your iOS version to the new iOS 5 you need to update your iTunes to iTunes 10.5 version.To download iTunes version 10.5 click here. If you already have iTunes 10.5 then escape this step.
Step 2:Open iTunes and connect your iDevice to your computer.
Step 3:Once iTunes has detected your device, click on the device name in the left hand menu and click on the "Check for Update" in the device description box.
Step 4: Apple will show you a popup message if an update for your device is available. Click on the "Download and Update" button.
Step 4: Apple will download the iOS 5 update and install it on your device. It is important that you DO NOT disconnect the device from the computer during the process. It is also recommended to keep your computer plugged in to the power outlet during the process.
Please be sure to make a backup using iTunes before you update iOS.
This may actually be the last iOS update you ever do over iTunes, as iCloud will allow you to download delta wireless updates from now on.Finally, the days of Apple charging for iOS updates on older devices are long gone. this one is free for all of those devices.