How to jailbreak iOS 6 using evasi0n Step by Step.

Step 1: Download evasi0n for Mac via our http://www.evasi0n.com/ and extract the package.
Step 2: Double click the evasi0n app to run it.
Step 3: If your device has a passcode set, unlock your device and go to Settings > General > Passcode Lock > and select Turn Passcode Off.
Step 4: Plug in your iDevice to your computer. This can be any device running iOS 6.x, except for Apple TV devices.

Step 5: You should see a message on the evasi0n tool that it has detected your device. Once an eligible device is detected, the Jailbreak button will become clickable.
Step 6: Click Jailbreak, and the jailbreak process will begin.

Step 7: Several automatic steps will now be performed, including preparing jailbreak data, injecting jailbreak data, rebooting the device, uploading Cydia, and uploading the Cydia packages list. This may take a few minutes, so be patient.

Step 8: Once the steps listed in step 7 have completed, you should now see a screen asking you unlock your device. Once your device is unlocked, you should see a new app icon on your Home screen called “Jailbreak”. Tap this Jailbreak app icon just ONCE, and the screen should go black and then return to the Home screen.

Step 09: You will see more messages like injecting jb data messages, and Root Filesystem successfully remounted on the evasi0n tool.

Step 10: Once the process is completed, you will see a “Done!” message on the evasi0n tool. Your device will now reboot. Be patient for this portion, because the first boot will take longer due to performing first time setup. Be aware that the device might restart several times.

Step 11: Your iDevice will now display a large Evasi0n logo sitting on a white background. The first time, you’ll see a series of brief (sometimes very brief) messages. These messages include:

• Setting up fstab and AFC2
• Setting up Cydia
• Setting up Cydia packages
• Clearing SpringBoard Cache
• Rebooting

Again, the first set of messages on the white evasi0n background are there very briefly, blink and you might miss them. Afterwards, your device will reboot for the final time. Once your device reboots, you’ll again be presented with the white evasi0n screen with several messages. This time the messages include the following:

• Initializing offsets
• Finding offsets
• Patching kernel
• Cleaning up!
• Done! Continuing boot

After these final steps, you’ll be taken to your Lock screen, signifying that the jailbreak process is completed.

The next step is to unlock your device, swipe over to the second page of your Home screen (or further if you have lots of apps), and open Cydia. On the first load Cydia will have to initialize, so this will take a minute or two. You’ll then be taken back to the Lock screen one final time. Unlock again, open up Cydia, and choose your user type.
Congratulations, your iOS 6 device is now jailbroken!

Video tutorial

How to jailbreak iOS 6 untethered with evasi0n - iPhone - iPad - iPod touch - YouTube