Many countries require a visa in addition to your passport. That visa can come in different forms: Visitor, student or work. In any event, the welcoming government would like to know your purpose in visiting the country and how long you plan to stay.
If you're going to any country, including your own, you'll probably need to work unless, of course, you're independently wealthy. For that, depending on the country's laws, you will most likely need that visa.
For a good starting place, why not contact that country's embassy to see exactly what you need to do.