This chkdsk /f is automatically executed by the windows system after resizing, because it detects changes in the file system.
Just after resizing ntfs, you close Gparted by clicking the "X" button, then you shut down the O.S. by the button on screen (choosing to reboot).
After rebooting in windows, chkdsk /f is automatically executed, and next the computer reboots, I think automatically too (in windows). You may see a message about some new device. You wait a few minutes (3-4), and you reboot in windows when there is no longer disk activity.
Perhaps this last reboot into windows isn't needed, but I prefer to be to the safe side .
*** It is highly recommended to backup any important files before doing resize/move operations. ***