Hello Gary,
I'm assuming an MG with standard 7" round headlamps.
You need to remove the chrome bezel, which normally has a screw at just off 6 o'clock then ease it off from the bottom.
The headlight assembly is held with three screws and normally can be removed by pushing gently inward and rotating it slightly, you will see what I mean with the bezel off. Then unplug the wires from the rear of the headlight.
Alec