Use tram number 2 direction Črnomerec. Buy a ticket from the tram driver 15kn(2€). Validate the ticket by inserting it into the yellow ticket machine. Ride the tram for the next 8 stations to the King Tomislav square:
Now you need to take tram number 6 direction Črnomerac and you have two tram station to the main square Ban Josip Jelačić. Your ticket is valid all the time in one direction!