How to make a zone flag

[Apoc.Index]

Not exactly sure how to do this, I was going over some of the PoTime quests to understand it better but I just cant figure it out.

Anyone able to give me a crash course on how to add a flag to a zone and write the script.

Here is the run down,
You need 3 heads, all from various targets, you return to the quest giver in zone (a) hand in the heads, he then flags you to access zone (b).

I am not an expert at scripting, I tried to muddle through the PoT ones but they elude me lol.

Thanks!