QuickPwn 3.x has not been released.

Steps: Download QuickPwn 2.2.5-2 for Windows. This will come in the form of a (compressed) .zip file.

Use iTunes to upgrade to the latest firmware. QuickPwn runs on already upgraded un-jailbroken iPhones.

This method does upgrade your baseband, which means it will negatively affect unlocked phones. You should read below for details.