Mrs. L. Those connections on the back are called Serial Connections.
There should be three. Printer, Modem and Keyboard.
Yes you would need an External Modem.
You don't have an Internal one in that machine.
It would have a special cable connector like your Keyboard Cable.
This would connect to the Modem "Port" as they're called.
PS. You don't have to apologize for what you don't know.
We understand. That's ok.
That's why we're here and that's what we do.
We're happy to give you the information you need.