When I open the ceiling fan in one of our rooms, I found out underneath the fan that there were 2 black wires, 2 red, 2 white and 2 green.

If I wish to install a light bulb, it was somewhat confusing which wire should I touch. There was 4 pair of wires in there. Could someone have basic electrical knowledge on how to install a light bulb please.

Thanks,

How are the wires currently connected?

White is neutral, green is ground, Both connected at Electrical Service. You should be able
To get bulb to light between Either of the hots or switch leg(red or black), and a other
Wire of bulb to white or green. White carries current, and ground does not,(Unless problem)