You need a (DC-)transformer (for your country) and a »connector« (and some tracks). That's all.
I don't know which electric system is in your country (where do you live -> Greece?).
So you have to take the transformer for your country (Germany: 220 V; USA 110 V;...).
DC-Transformers of Playmobil or LGB (in Germany):
• 0 to about 16 volts
• Connection: in FRONT/RED+BLUE (side/black+white is for lightning,...)
4375 (D german Version)
4378 (UK Version)
4379 (US Version)
or (only Germany?):
4350
4359
Connectors (to connect the transformer to the track):
4351
4372
LGB 50160 (better connection than Playmobil 4351/4372)
E.G.: If it is Greece (same electric system as Germany):
Playmobil
4375 (german Version) or
4359 (more power!) +
LGB 50160 (for better connection, but Playmobil 4372 also is ok).
Good luck (ask if there are more questions)!