Hi!
From the train station it is very easy to go to KTEL Chalkidikis, you just take bus number 45. It is an express route, so it is also the fastest choice. Just ask for the right bus stop, because you may end up going towards the other direction (KTEL Makedonia).
From the court house (Eikostis Ektis Oktovriou street) you can either walk to the train station (it is very close), or take a taxi, or take a bus and once you reach the train station, you will take bus number 45.