Hello I am trying to script my map so that the AI will follow the player as they move between fire positions. The data file for my map doesn't show in the data folder. Can anyone send a tutorial or explain?

The data folder is where raw assets go, and then we use tool to compile them into tags, which go in the tags folder. Your map before its compiled into a .map is a .scenario tag, which is usually located under the levels folder in your tags directory.

For custom maps, we need to manually create folders in the data directory for our maps data (scripting, bitmaps, bsp).

For example, if your custom map is located in
"tags\levels\custom\custom.scenario"

then your data folders would need to be
"data\levels\custom\bitmaps\bitmap.tiff"
"data\levels\custom\models\bsp.jms"
"data\levels\custom\scripts\script.hsc"

To make AI follow you, add the command in a script. Make sure the AI exist by that point and you have their firing positions set up for following.
"ai_follow_target_players encounter_name"

If you still have trouble, make sure Halo isn't installed under the "Program Files" directory, because your data will not save.