iCloud backup isn't in iTunes (iTunes for music, books pics sync). To access iCloud with your PC, you have to go to the actual iCloud website using your PC
http://www.iCloud.com
(which, BTW, you cannot access using an iDevice - weird)
On your PC, you will find a very nice version of your iDevice presentation of email, contacts, calendar and another (can't recall at the moment), complete with the textured gray backgound and iDevice icons. I've made this my home page on Firefox or Chrome and, especially Chrome, it works very well. Bridges the PC-iDevice gap.