Simples. From a Power Shell type (copy/paste) the following;
w32tm /config /manualpeerlist:pool.ntp.org /syncfromflags:MANUAL
And that’s it. The pool.ntp.org is a round-robin of random selected NTP servers. As they say “This is usually good enough for end-users“. But you might want to add several NTP-servers yourself for redundancy?
Then for the client machines you need to RUN as Administrator the following;
NET TIME /domain:mydomainname /SET /Y
And that’s it!