I don't know your computer but if it's a desktop machine it probably
has not got a Bluetooth adapter built in. You can buy them fairly
cheaply (under $20) but getting them to work with Linux is another
matter. I gather you have both headset and adapter, either USB or a
card in the computer.

Sorry I can't be of any further help to you as I must admit that I
never got Bluetooth to work with Ubuntu, although it is supposed to.