Not your fault. It's far from being as obvious as it could be. Go to Settings > iCloud > Storage & Backup You'll see a switch to turn the backups on/off. Under that you'll see a Back Up Now option. If you continue to the Manage Storage option you can see what apps are storing documents and data in iCloud, as well as how much space your Mail app is taking. Select your device from this screen and you'll get even more information. The date of your last backup. The size of your current backup. The size of your next backup. The ability see how much space each app will take to backup, and to turn on/off which apps get backed up. You can also delete the last backup, which will sometimes jump start the backup process again; especially if you then force a backup as described earlier. Hold in mind that if you delete the backup and then start a new one it will take longer. Usually the iPad only updates the current backup with changes, which is much faster. Good luck.