Why does this happen that IPSW is not supported by this version of redsn0w extra information you have a iPad 2 6.0.1 and you have the latest redsn0w which is 0.9.15b3.please help?

The error indicating that the IPSW is not supported by redsn0w often occurs because the specific firmware version you're trying to jailbreak is not compatible with the version of redsn0w you are using. In your case, redsn0w 0.9.15b3 may not fully support the iOS version 6.0.1 on your ipad 2, or it might require a specific IPSW file that is correctly signed or compatible. Make sure to download the appropriate IPSW file for your device and verify that it's the correct version. Additionally, consider checking for updates or alternative jailbreak tools that may support your firmware.