[SundayDuffer]

run winpwn 2.5 in expert mode...it's a GUI interface app, just follow the screen to make your custom firmware. Once done, plug the phone in iTunes...click Shift and Restore...then go choose the custom firmware that you had built, and let it runs.

to put your phone in DFU mode....hold both power button and home button til the screen goes black, then let go of the power button, continue to hold the home button til iTunes recognizes it....then click Shift and Retore to choose your custom fw.