Let me try and help you here.
Ok first what version is currently installed on your Apple TV?
If your Apple TV is version 5.3, but Seas0nPass is not able to download the IPSW file you can download it here manually - http://www.idownloadblog.com/download/
All you do is download the version your Apple TV is currently as, and save it on your desktop (best place) open seas0npass and then hold alt and click Create IPSW. A pop up should appear, now locate the file you downloaded and select it. Seas0npass will do the rest automatically. You will only need to put the Apple TV into DFU mode with the remote when Seas0nPass asks you too.
If you have any issues let me know.