Tutorial instructions: 1) The first thing you are going to need to do is ensure your iDevice is running the iOS 4.2.1 firmware. This is the only firmware version that greenpois0n RC5 supports. 2) Once you are running a clean install of the iOS 4.2.1 firmware, download greenpois0n RC5 jailbreak tool. 3) Double click the downloaded greenpois0n-windows_rc5_2.zip file to extract the archive then double click greenpois0n from the desktop to launch the application. 4) Connect your iPhone to the computer, power it off, then click the large Jailbreak button.