In this video from faintstarlite we learn how to jailbreak an iPhone 3GS step by step for beginners! Your iTunes needs to be running 3.0 and you must use a windows computer. Plug in your iPhone to your computer. Go to purplera1n.com and download the program. Your iPhone will now reboot and it will load up with the Purple Rain icon. Now click on the Freeze icon and install Cydia which then allows you to download programs on your iPhone. You will need this to download ultrasnow which unlocks your phone. Installing Cydia will take a few minutes. Make sure your Wi-Fi is on. After Cydia is installed, restart. Before continuing now, click on Settings and go to General and to Network. Turn off 3G if you are putting T-Mobile on your iPhone. Now click on your Cydia icon. Once in Cydia click Sources, Edit, add, and type in repo666.ultrasn0w.com. Now go to Changes, and install ultrasn0w. Now reboot. Now use a paperclip to take the SIM card out and replace it with your own T-Mobile SIM card. Now reboot, and you can make phone calls on your own network! Try it and you can disable the sim lock in your iPhone.