Step 1: Download redsn0w 0.9.10 beta 6 using our Jailbreak Programs Tool
Step 2: Download your device firmware using our iOS Versions Tool
Step 3: Open redsn0w and load the ispw downloaded at step 2
Step 4: Put your phone into DFU mode. If all went good, you will have a finish button.
Step 3: Now put your device in DFU mode again
Step 3: If you did not closed redsn0w, push the Back button and then Extras. Load the ispw again
Step 3: Press just boot.
You should have a jailbroken device