i am trying to update iphone 4 fro itunes - itunes does not show any devices in menu

Make sure you are running iTunes 10.6.3 or later. If you aren't, update iTunes. If you are, see the troubleshooting steps here: iPhone not recognized in iTunes for Windows

You should be able to do the over the air update thru settings, general, software update.

I do not recommend using wi-fi to update to iOS 6. iOS 6 is a major update and I highly recommend using iTunes (make sure iTunes is version 10.7 or later)

Either one is fine, the only time OTA updates are harsh is when the new ios comes out and everyone is downloading it and it puts a strain on the system.

Also, in response to the 10.6.3 iTunes version, it needs to be iTunes 10.7 or later

eeeeee5462 wrote:

Also, in response to the 10.6.3 iTunes version, it needs to be iTunes 10.7 or later

Incorrect. That's only true for the iPhone 5. You can install and sync with iOS 6 with earlier iPhones with iTunes 10.6.3.

You techincally may be able to, but there will be problems... whether it is in the initial download/install stage or after you have already started using the device . I promise.

That's not true either. There are many people using older PowerPC Macs that can only run OS X 10.5.8 and therefore can only run iTunes 10.6.3 and they use iOS 6 without any issues. This backwards compatiblility was maintained in order to allow people with older computers to still work with iOS 6 devices. It's only incompatible with the iPhone 5.