Then in a terminal window, do
mkdir ~/binif you do not yet have a bin folder in your home folder.
In the bin folder, put the script file settim. Edit the file to see what is in there. You will not need sudo if you are logged in as root. Then in a terminal window, do
chmod a+x ~/bin/settim
You will want a menu item to activate the script. Put ntptime.desktop in folder ~/.local/share/applications/. Edit the file to change username into your username or change /home/username into /root if you login as root. To be sure, go into terminal and issue the command pwd. Put icon clock.png in ~/.icons/. My menu item ends up in System/ Preferences/. Don't ask.