The tutorial is for iPhone 3G any firmware version installed. After completing this strictly, you'll get a 3G iPhone with the latest firmware and all functions unlocked (jailbreak).
If you do not know the words: "Jailbreak", "unlock", "firmware", etc.. dedicated page and read the terms if you're not convinced to read your release and list several reasons.
What do you need?An iPhone 3G + USB cable and a PC with Windows installedFirmware 3.0 (download)Redsnow 0.7.2 (download)iTunes 8.2 (download)
Download the firmware 3.0 and redsnow utility (the latter requires unzipping) and then install iTunes version 8.2.
Connect your iPhone to your computer via USB cable and open iTunes.
In iTunes, select iPhone in the list on the left and then hold down "Shift" and select "Restore." In the new window navigate to the firmware file downloaded in step 1 (iPhone1, 2_3.0_7A341_Restore.ipsw), select it and click "Open". iTunes will now install the latest version of your iPhone firmware. (Takes about 10-25 minutes, do not interrupt the process).
After the iTunes restore operation completes (Update) expects the iPhone to be recognized by iTunes to activate the network (if you use the phone in the network is encrypted). Start redsnow utility downloaded in step 1 and reconnect iPhone to your computer via USB cable.
Click "Browse" and navigate to the firmware file downloaded in step 1 (iPhone1, 2_3.0_7A341_Restore.ipsw), select it and click "Open". After its processing, the utility will display the message "Successfully Identified IPSW. Click "Next" to proceed to next step (redsnow will begin processing firmware).
Tick "Install Cydia" and click "Next." On the next screen appearance, make sure the phone is closed and connected to a computer via USB cable. Immediately after clicking the "Next", the utility will guide you to enter your phone in DFU mode. You will be asked to: press the Home button for 5 seconds, press Home and Power buttons simultaneously for 10 seconds, press the Home button just below, not Power, until the iPhone into DFU mode (30 seconds) .
Redsnow Jailbreak will begin operation. The display screen is posibiltiatea the latest iPhone still work, is allowed to complete all operations.