(This is for Azerothcore)
I think you can start with https://www.azerothcore.org/wiki/dbc-areatrigger
and https://www.azerothcore.org/wiki/areatrigger_teleport
then see how an area teleport is made:
For example,
You have to open your game database.
id 45 in aretrigger database is the teleport to the scarlet monastery (graveyard) instance. It has a map id for the map it is located in (0 = Azeroth / Eastern Kingdoms) then a position for the center of the area trigger and its radius. The rest are 0, but are used for a box trigger and not a spheric trigger.
If you then go to id 45 of areatrigger_teleport to add the target map and the position + orientation of the teleport destination.
After you made your areatrigger, then attached a teleport to it, you just have to place your doodad around the area. But the doodad itself will not have any teleportation property.
I hope this helps.