OK, so now you could use WinReducer with a good basis.
1) Do you have a Windows 7 ISO ?
2) If Yes : launch WinReducer 7.0, use "START" button, then "ISO" button
3) Hit "Yes", in the warning message
4) Then choose your ISO file (don't worry this will not be deleted, just extracted), depending on where you keep it
5) Wait few minutes, during extraction process
6) Once extraction process is finished, you will see a new small window with a big "MOUNT" at the top of it
7) Just below this "MOUNT" button, just select your Windows Edition according to your Serial Numbers (you need to choose the good one, otherwise your installation will fail !)
8 ) Now, you could hit the "MOUNT" button !
9) Wait until the configuration finish
10) then you will have access to all 850 settings available
11) Try to modify few components
12) Then go to "APPLY" tab and hit the Launch button
13) once the process is finished, you will see an ISO creation window
14) Choose how you want to save your changes
15) then hit the create button
Tell me if you experience trouble !
PS : If during all the process you experienced an error, just close the windows, exit winreducer, restart your computer, launch winreducer, exit it again (to be sure to properly clean your previous test), then launch winreducer and restart from point 1) ...