Ok. Good. I have a Windows 7 box handy. :)
Unfortunately, it is not as easy to manipulate permissions on Windows as on Linux. You need to browse to the directory in question and right click it to get the popup window. Find 'Properties' at or near the bottom and click it. You'll get another window. Go to the 'Security' tab. Now look at the Group and User name list, then look at the window below that list. Those are the permissions for that file or folder for the several groups and users. If you click on the 'Advanced' button, and then go to the 'Owner' tab you can see who the file owner is. By clicking yet another button, 'Change Permissions', to get yet another window you can edit the permissions. You'll need to compare a working theme with a broken one, so lots of button clicking.
If it were Linux I you could run
ls -l in the parent directory and get the same information and more in a nice neat list. I love Linux. ;)