It's much more easier than it seems
There's maybe a graphical utility to do such things, but I don't know it. I prefer text mode for configuration purposes.
So If you want to allow everyone read/write/exec /mnt/windows directory and these sub-directories: edit /etc/fstab as root. Reper the line containing /mnt/windows and in the options column, add: umask=000.
If there's something you don't understand, or if you want a more precise configuration, tell... We'll explain you