How to jailbreak iOS 5.1 using Redsn0w
images step by step Here
Step 1: Download the latest version of iTunes (10.6)
Step 2: Open up iTunes, and back up your device.
Step 3: Upgrade your firmware to iOS 5.1. [download links]
Step 5: Start Redsn0w, select “Jailbreak” then “Install Cydia”. Follow the steps to place your device into DFU mode.
Step 6: Now we move on to the process where you will need to repeat every time your device is switched off. This is called tethered boot. Launch Redsn0w, select “Extras”, then”Just Boot” in order to boot your device tethered.
Booting Semi-Tethered (Optional)
The “SemiTether” patch may work through to 5.1. It’s a cross between tethered and untethered – allowing you to boot your device without a computer, but the available features are somewhat limited, so you’ll need to boot tethered through Redsn0w in order to enjoy a fully-functional break. It’s free, and available over at the BigBoss repo: http://thebigboss.org/semitether.