If using Time Machine to back up to a network disk, you can verify those backups to make sure they're in good condition. Press and hold Option, then choose Verify Backups from the Time Machine menu. In OS X Lion v10.7.3 or later, you can start up from

Back up with Time Machine. Time Machine is the built-in backup feature of your Mac. It’s a complete backup solution, but you can use other backup methods as well.

Check Back Up Automatically in the left pane of the dialog box if you want your Mac to back up at regular intervals. Check Show Time Machine in menu bar to create a shortcut in the menu bar to Time Machine preferences and backup status.