Here is how you get the editor, regardless of how you installed the game:
- Go to your GoW installation directory.
- Open 'Binaries'
- Right click Startup.exe, highlight Send To, and click Desktop.
- Right click your new shortcut, and go to properties.
- In the 'Target' box, go all the way to the end, and press space. Then type 'editor'.
Now run your shortcut. It may take awhile.
I hope this helps. I created it to help prevent all the "Where's the editor???" threads.