If you want to use iOS 7, you will need iTunes 11.1. It’s available now through your Mac’s update menu or through the download page.
Just head on over to the iTunes page, and download.
If not, you can use the Mac App Store and check on the Updates tab. This will download the latest version of iTunes for you.
Once that’s all done, you have iTunes 11.1 and can sync your iOS 7 devices.