The reason that this is not happening is that you forgot about the initial import of your data into fruux.
Modern CardDAV and CalDAV based synchronization doesn't automatically "mix and merge" data that you already have on your device. On your device there are different "buckets", e.g. a local one, with data that is only stored physically on your device as well as a "fruux" one. The device will never mix or merge data in different buckets. That's the reason nothing is showing up in our webapp (or on other devices you may already have set up) yet. Your device is syncing, but right now it's syncing an "empty bucket".
To change that, export your existing data on your device (calendars and tasks lists in iCalendar .ics format and contacts in vCard .vcf format) and then use the "Import" button (bottom left in the fruux contacts, calendar and tasks webapp) to get that data into fruux.
Once the data is in fruux, it will automatically sync to all of your devices and any changes you make on any of your device or in our webapp, will automatically sync too.
How to avoid duplicates and confusion:
After you've confirmed that all of your data is in fruux and correctly syncs with all of your devices, you may also delete the "local buckets" to avoid getting confused (because now you know: If you'd make a change in the "local bucket", it wouldn't sync) or having duplicate data (identical data in the "local" and the "fruux" bucket) on your devices.