where do i get the operating systemupgrade for my apple 4s?

If your iDevice is using a version of iOS lower than 5, you will need to use iTunes on your syncing computer to perform the upgrade. Use the Apple link below as a guide for the upgrade.

http://support.apple.com/kb/HT4972

Also read the instructions from the section entitled "Update your device using iTunes" at the link below.

http://support.apple.com/kb/HT4623

Information regarding transferring purchases from your iDevice to iTunes on your syncing computer can be found at the link below.

http://support.apple.com/kb/ht1848

With iOS 4 you will have to attaché to a computer running iTunes, select the iPhone from the devices listed in the left panel of the window, then in the main Summary window select Software Update.