The new one must have been in inventory for a while or it would have the latest iOS.
To update it, connect it to your computer and open iTunes. You may be prompted by iTunes that a newer version is available; if so, choose Download and Install to update it to iOS 6.1.3.
If you don't get this prompt, click on the name of your phone in iTunes, then click on the Summary tab at the top. On the Summary tab, click Check for Update. You should then be prompted that there is an update available and you can update your iPad.
After updating, as mentioned in the posts above, set it up as a new iPad, eject it from iTunes and disconnect it from your computer, then go to Settings>General>Reset, tap Erase All Content and Settings, go back through the setup screens on the iPad and when given the option, choose Restore from iCloud Backup. You should now be able to choose your backup to restore from. Be sure your iPad is connected to wifi and your charger as this may take some time to finish.