Step 1: Download Device firmware and Redsn0w0.9.6 RC17, Latest iTunes, then connect your iPhone with computer.
Step 2: Choose the iPhone Restore-ipsw file.
Step 3: Please click "Jailbreak Monte" option on screen, choose iOS 4.3.3 firmware file.
Step 4: Power off your iPhone before PLUGGED IN to computer. Then press Next button to continue.
Step 5: Enter DFU Mode. The screen should be blank.
Step 6: Let Redsn0w do the rest job. Then as it instruction, jailbreak will be done.
The jailbreak steps well done!
links to download the files
1. for idevices firmware http://www.felixbruns.de/iPod/firmware/
2. Itunes http://www.apple.com/itunes/
3. Redsnow https://sites.google.com/a/iphone-dev.com/files/home/redsn0w_win_0.9.6rc17.zip?attredirects=0&d=1