Just to be clear (I can read your request 2 different ways), fog doesn’t care about the source image or how its setup. FOG only moves disk blocks from the source computer to storage on the FOG server and then from storage on the FOG server to the target computer. How you prepair the reference image before cloning and what happens to the target computer after FOG is done is up to the IT technician.
But in general terms, for MS Windows you will want to setup the computer in audit mode to perfect how you want the target computers to appear, then sysprep the reference image and power it off (using a sysprep command line option). Then you pxe boot the reference image with FOG and capture the image. On the target computer side, you register the target computer with FOG. Then you assign an image to the target computer and create a deploy task. When the target computer is pxe booting FOG will image the computer then reboot it. On the first reboot the target computer will startup OOBE/Winsetup to complete the installation on the target computer, at this point of the first boot of the target computer FOG is no longer involved with the imaging process (said knowing that if the target computer is configured appropriately the FOG client will carry out an required post install commands).
There is a wiki page that describes capturing your first image that you might want to look over: https://wiki.fogproject.org/wiki/index.php?title=Booting_into_FOG_and_Capturing_your_first_Image