Assuming that you are referring to an A body instrument cluster, there will be a circuit board behind your gauges similar to the one pictured. A series of bulb sockets are installed in those larger holes and are removed by rotating them 1/4 turn.
I had a problem with my dash lights not working a while ago, I replaced all the dash lights and still nothing. The problem was the rheostat, or dimmer switch, after you replace the lights if they still dont work then that is your problem, I just sprayed some contact cleaner on it and it works fine now.