How can I load the latest version of iTunes so I can sync it wth my desktop?

iTunes is not a separate app on the phone. It is built into iOS. If you are getting an error message when you try to update of sync, it is the verion of itunes on your computer that needs to be updated. http://www.apple.com/itunes/download/

Have you downloaded iTunes 11 & tried to install it?

If your Mac is able to run it should install, Apple list the spec on the download page. Does your computer meet them?

Post back info about your computer if it won't install.

The problem more than likely lies with iTunes for windows, not the iPhone. You may wish to try here: iTunes for Windows

I haven't run iTunes on a windows machine in years, so not really sure what direction to point you in other than that.

Have you restarted your computer?