Modding Windows 7

I have seen many modded win7 releases such as Windows 8 xTreme,Windows 7 Gamers edition etc.i want to know how to mod windows 7.Can someone please provide a tutorial.
thanks.
Answer #1
I think you need extensive background knowledge on programming and operating systems before
you can just jump into modding OS’s
Answer #2
http://lmgtfy.com/?q=Modding+Windows+7
Answer #3
I think you need extensive background knowledge on programming and operating systems before
you can just jump into modding OS's
Agreed to some extent IF You want to make a Package installer of your created Mods.
Modding Windows is easy,But trying to make Registry & Package installer can be difficult.