On your demo site, I have seen some default locations, will be able to change these with the ones of my country?

Yes, using the admin panel and the Settings->Locations page there, you could easily make changes in the default locations or create your own location lists. We also have ready location lists for most of the countries in the list, which we can provide asap and for free - to check the locations we can provide for your country, you could just contact us and we'll forward you asap after that the ready list we have.