Yea.... It's kinda risky purchasing the iPhone without doing any research.
Though, I believe they will ask u to sign up contract with them before u
able to buy the phone, aren't they? Unless you buy the outright one... Yet,
it might be locked version.

Google around for unlock... Tons of info out there, read them up then I'm sure
by then you will get the idea what that is.

I think once u watch the Guided Tour, you will have most of your questions answered... hope you enjoy learning it....