Where did you get a harness with no instructions? Anyhow, you will have bulbs for each of the cluster sockets and the high beam indicator goes in the bottom center of the speedometer. I think that you should also have a bulb in the ignition switch bracket. Also, the bulb for the high beam indicator is a smaller bul than the others although this really doesn't matter.
If your parking lights are original style, the socket will not just pop out, I would think.
