How to update my iPhone 3GS to iOS 6?

I connected it to iTunes, clicked on 'Version: Update' but this error message comes up:

'The iPhone software update could not be contacted. Make sure your network settings are correct and your network connection is active, or try again later'

What does this mean? What are my network settings?
I tried this last week and the same thing happened.

LOL the 3GS is ancient. Throw it away, where it belongs, and buy an iPhone 5 like everyone else.

Go into General and Software Update.

Just do a system update but the technology is not as good and could crash a lot if you upgrade and run IOS 6