You'll have to remove the whole instrument pod. Once removed you'll have to remove the nine screws that secure the back panel and the odometer reset knob that requires a firm pull. Carefully remove the back and try not to damage the rubber gasket. with the back removed you will see the black plastic sockets that hold the removable globes. Most electronic stores will stock them, you can also upgrade to LED globes in different colours, however LED's are polarity sensitive so connect the pod without the back to make sure they are the right way around.
Regards Martin.