iCloud doesn't upload ANY data to the cloud

Hi, it seems iCloud doesn't push my data "to the cloud" as it should. I don't have an iOS device yet, but I'd love to sync some of my data to my Bootcamp partition and Windows machine at my work. For example, here you can clearly see my Adress Book.app window populated with a lot of contacts with names, pictures and phone numbers:

So I've set up my iCloud preferences to sync "Contacts", "Calendars" and "Bookmarks":

But once I open http://www.icloud.com/ and login with my account to check my contacts, there's only one single contact - ME.

Actually, iCloud didn't transfer ANY information. So am I doing something wrong? Should there be a button like "Push it into the cloud" or "Update" somewhere? Shouldn't this information be updated automatically?