I have an IPod touch 4 6.1.6 and I want to jailbreak it how?
This is from the Jailbreaking iOS 6 guide.
Basically, what you do is a tethered jailbreak through redsn0w, and then you download a special package in Cydia that will make the JB untethered.
To jailbreak your iPhone 3GS, iPhone 4, or iPod touch 4th generation on iOS 6.1.3/6.1.5/6.1.6 using redsn0w:
If redsn0w gets stuck in the reboot process, your antivirus software is probably silently interfering with it. This is a known issue. The only antivirus products known not to interfere with redsn0w is MSE (Microsoft Security Essentials / Windows Defender), and some people have said that Kaspersky doesn't affect Resn0w either. Any others should be disabled, or, if that doesn't work, uninstalled.
This answer is marked "community wiki".