You cannot jailbreak ios6.1.3 on IPad 3. evasion supports untethered jailbreak up to 6.1.2. Can only do tethered jailbreak 6.1.3 on A4 chips and below using redsn0w. However I understand ios7 I being released on 10 September. Maybe after a month or so then the jailbreak will be out which supports 6.1.3 up to iOS 7.