You're probably just fine with either set of strings. It sounds like you bought a nylon-string guitar, and it is set up normally.

The lower, metal strings are called "wound" strings. And they are like a tiny brass wire wrapped around an inner filament. In your case, that inner line is likely nylon fiber.

In the case of a "steel string guitar", the higher strings would look like wires, and the lower wound strings would contain a metal inner filament (like thin wire). [br][br]

Hope this helps a little!

-Lisa