Controller (Capture the flag script), can someone help?

So I am trying to make a controller game type for my game, where whatever team controls the most flags out of the 3 flags before the time limit wins. I know how to make the flag go up and down (to represent it being captured/controlled) but I have no idea where to start when making the script that changes the colour of the flags when players are in a certain zone and capturing the flag and a script that puts how many flags the 2 teams are controlling at any one time.

I'm only a beginner at scripting (can do basic stuff) but it would be a real help if someone could help me with this script or at least point me in the right direction.